Why didn't the Trace give young Tom away?

I still haven't been able to figure out the "Trace" and, to be honest, I'm not sure J.K. has either.

If I recall correctly, the Trace was first mentioned, perhaps not by name, in The Chamber of Secrets when Harry receives a warning from the Ministry after Dobby's infamous Hover Charm that dropped a big frothy dessert on Aunt Marge. As it developed, the Trace is explained as some kind of charm that attaches (automatically?) to underage witches and wizards to permit the Ministry to "trace" when they perform feats of magic outside school and only lifts once the particular person comes of age.

I wonder, by the way, if the Trace is what permits Hogwarts to locate Muggle-borns with magical powers and then invite them to enroll when they become of school age. But that's an aside...

In The Half-Blood Prince, Dumbledore explains to Harry that the Ministry "can detect Magic, but not the perpetrator" -- that the Trace gives Ministry officials notice only that an act of magic has been performed in the vicinity of an underage witch or wizard. If there are adult witches or wizards nearby, the Ministry simply assumes the magical act was performed by an adult and takes no action. Further, Dumbledore tells Harry that the Ministry cannot tell the difference between House Elf magic and human magic, so Harry took the blame for Dobby's Hover Charm.

A lot is made of the Trace in The Deathly Hallows since Harry, who doesn't turn seventeen until his birthday during the summer before seventh year, cannot start his search for the Horcruxes until the Trace is lifted. After his seventeenth birthday, when Harry, Hermione and Ron encounter Death Eaters in the coffee shop immediately after fleeing the Weasley wedding, Hermione wonders whether perhaps the Voldemort-controlled Ministry has found a way to keep the Trace on Harry even though he is now of age.

Ron objects: it's not possible, he says. The lifting of the Trace at 17 is wizarding law.

So that's the stage against which I ask the following question: in the HBP, why did the Ministry not know immediately, via the Trace, that an underage Tom Riddle had performed the three Avada Kedavra spells that killed his father and grand parents?

Dumbledore explains to Harry that the Ministry did not trace young Tom's magical acts in Morfin's presence because they simply assumed the adult wizard (Morfin) had performed them. But he also tells Harry that "we can be fairly sure what happened. Voldemort Stupefied his uncle, took his wand, and proceed across the valley to 'the big house over the way'. There he murdered the Muggle man who had abandoned his mother, and, for good measure, his Muggle grandparents."

Yet, the Ministry failed to recognise that it was young Tom who killed his Muggle parents, an act that was apparently witnessed by no other person, Muggle or Magical. Should not the Trace have made it very clear to the Ministry that the three Avada Kedavra spells were cast by the only magical person in the vicinity, the under-age Tom Riddle?

Is it possible that Tom forced Morfin to accompany him when he visited the Riddle house to commit the murders, thus leading the Ministry to be more ready to blame Morfin? That would have made the act much more difficult to accomplish, especially without attracting notice from passersby, but it would at least address the potential Trace-related issue.

Another side question arises: why would the Ministry not place a Taboo on the three Unforgiveable Curses so that they have instant notice that the curse has been used and can arrest the culprit immediately? Sure, the Taboo likely only works on words that are spoken out loud (rather than simply thought) but I don't recall a single instance when Avada Kedavra is used, for example, that it is used nonverbally.

The Taboo should have been taboo for J.K.

Let's talk about the "Taboo" for a moment.

We're introduced to the Taboo mid-way through The Deathly Hallows. Ron explains that Voldemort's name has "been jinxed, Harry, that's how they track people! Using his name breaks protective enchantments, it causes some kind of magical disturbance... Anyone who says it is trackable!"

First of all, I agree with Ron. Voldemort and the Death Eaters make very clever use of the Taboo since they know that only people who are members of the Order of the Phoenix or might otherwise prove a threat to the Dark Lord still use the name "Voldemort". The Death Eaters refer to him as "the Dark Lord", for the most part, while the good guys and innocents all prefer to use "You Know Who" or "He Who Will Not be Named".

So placing the Taboo on the word "Voldemort" will provide excellent results for the Death Eaters: they will be able to track really problematic people with few false alarms.

Clever. Very clever.

But let's look at the Taboo itself. As explained in the book, the Taboo allows me to place a jinx on a word so that if you use that word you lose all magical protection that you have sought to place on yourself and I can track where you are.

Wow. That's a pretty powerful tool. And we see it work very powerfully later in The Deathly Hallows when, despite all of their tried and true protective enchantments, the Taboo exposes Harry and the crew to the clutches of the Snatchers.

So why isn't it used more often? For example, if the Death Eaters were so interested in finding Horace Slughorn prior to the events of Book Six, why didn't they just put a Taboo on his name (or on "candied pineapple") in order to find him? Sure, there might be some false alarms but they'd probably be worth the trouble.

Why would they not put the Taboo on the names of all of the Order members in order to find them and break down the enchantments protecting them.

And remember, at the start of The Deathly Hallows, Snape tells Voldemort that, Harry will be taken to a safe house that has been prepared for him and has been "given every protection that the Order and Ministry together can provide". Snape concludes: "there is little chance of taking him once he is there."

Wait a minute? If capturing Harry is job one and they have a weapon as powerful as the Taboo available to them, why wouldn't they try jinxing a whole bunch of names or words associated with Harry and the Order, accepting that the large number of false alarms they might face would be well worth the possibility that the Taboo would eventually beak all of the protective enchantments the Ministry and the Order have put in place and allow them to track and capture Harry?

Let's just say they Tabooed the word "Hagrid"? Wouldn't that be enough? I mean, not that many people would say Hagrid's name about then but members of the Order are sure to do so. Why not use it to track Harry and strip away his protections?

Again, I think the Taboo is a very interesting idea. And I agree that the Death Eaters were very clever to have used it to expose members of the Order.

But, like the Time Turner and Felix Felicis, I wonder if it wasn't a dramatic mistake for Rowling to introduce the Taboo into her world. Once she establishes that this powerful tool exists, she has to consider when and how it might otherwise be used to effect in the story.

Then she has to account for why it was not used (it is an extremely difficult jinx and a person can only cast one Taboo at a time, for example).

If she doesn't, in my opinion, she undermines the drama of her narrative.