The police can also be technically inept and put out bad information when it comes to phones and computers. Tracking cars for home burglary I can understand, but I don't get how AirTags is even needed or useful for car thefts. If the thieves already have physical access to said expensive car, why can't they steal it where they found it or physically follow it home? Even if they do need a tracker to steal that car, why not use one that doesn't risk notifying the owner that someone else's AirTag is with them?
I think the key point here is that cops have actually
found AirTags on cars, so naturally that's what they're focusing on. It's unclear whether there's any direct evidence of them being used for thefts, or whether the cops are just assuming that AirTags flund by owners are being used for this purpose. We don't know in the case of the York police report whether the AirTags were found by owners or in a vehicle that was recovered from thieves. Even if these were only reported by the owners, it's probably a fair assumption that they're being used by crooks.
You're right that it doesn't make much sense to use AirTags to steal a single car, but it's safe to say that these are being used by organized car theft rings that are out to do a volume business.
Stealing a car from a mall parking lot draws too much attention. Stealing multiple cars from a mall parking lot draws even more. The best time to do this is under cover of darkness. Most car thefts — at least those in this area — happen in the wee hours of the morning, when everybody is basically asleep.
Physically following a car home takes a lot more time. Sure, that's fine for stealing one car, but if you're looking to pick up a dozen or more in one night, you don't have time to follow them all home. After all, it's fair to say that most criminals are inherently lazy, especially those on the lower rungs of the ladder. The game is about maximum payoff for minimum effort. If crooks were willing to do real work for their money, they probably wouldn't be stealing cars in the first place.
As the cops said in their bulletin, before AirTags came into the picture, most cars were stolen by thieves driving around neighbourhoods late at night looking for targets. They're probably still doing that, but this presumably makes it even easier. The crooks can basically wander through a mall parking lot, pick out their intended targets, and quite literally "tag" them for later. Then they can organize the pickups more efficiently by going straight to the target vehicles.
Not every one is going to pay off, of course. Some will be in garages, or have other security systems in place which make them not worth bothering with. Some of the AirTags will also be found before they can be of any use — although keep in mind that if you don't see the "Unknown AirTag" alert until you get home, it's already too late to hide. Some people may take extra precautions after seeing that, but others might not understand why the AirTag was planted on their vehicle in the first place, and not everyone will think to call the cops right away. People can be naive when it comes to this kind of stuff (e.g. "Huh, this is weird. Maybe I should talk to somebody about it. Well, I'm tired, I'll deal with it in the morning...")
Still, however, this is another reason that AirTags are so attractive, since they're cheap and easily obtainable. Scatter a few dozen around cars in a mall parking lot, and even if only a few lead to stealable vehicles, the thieves still come out ahead.
According to the Toronto Star investigative report I linked to earlier, this also seems to be a team effort in many cases too. Groups of thieves are paid to steal the vehicles, drop them in a common location such as a park, and then go back and grab another one and do the same. Another group rounds up the vehicles in the park, taking further steps such as disabling their built-in GPS tracking, and then ferries them to their next destination, which is often a cargo container at a railyard to ship them out to their next destination. The days of local chop shops seem to be long over, as it's far more profitable — and less risky — to ship them overseas.
