The technology is in game. Said technology could probably use some love anyways.
Allow the outside of cars to be bugged for tracking instead of chalking them. There is already equipment in game that can counter it too.
That is all
#2 I'd recommend familiarizing yourself with the trackers in game to understand why you could still hire people out. (FOIC)
#3 It would remove the meta of unattended/ambient vehicles as they wouldn't move so you could never safely assume they weren't being used.
#4 Every attempt at doing this would cost you more than a sliver of chalk and there'd be inherent risks to bugging someone's car.
#5 As with above, no one would be frivolously bugging vehicles without gathering paydata and RPing first (See 1&2)
While Those are certainly valid points, there is one thing in particular that I take issue with in your thought process.
You cannot prove a negative, you can only increase the probability of it being true. If a vehicle is truly abandoned, then it's impossible to verify that as the case based solely upon observation of the vehicle, and that would never (under what you just said) justify bugging a vehicle that you perceive as abandoned, because you would never see anyone interact with it.
While I do think bugging cars is a good idea, I don't think it in of itself negates other ideas and avenues of information gathering.