It's quite simple, there are many different types of tea leaf all with different goals. There are some out there who are very very good at what they do and some who are complete idiots who couldn't steal a car with the keys left in the ignition. Much the same as everyone who has a job, some are useless and some are very good at their jobs.
It's the useless idiots that are more of a peril. If a pro wants your car, you won't even know about it until you go to where you last saw it. The goons are the ones that leave a trail of collateral damage - handy for the Police but not very good for the rest of us who end up footing the bill, directly or indirectly.
My earlier point about motors being nicked for parts is based upon this latter type of oik, and the interchangeability of parts over a long production run, where (say) unscrupulous car dealer finds it easier to have a mate nick an elderly (but, naturally, immaculate!) high-mileage motor to provide donor panels for a more recent, low-mileage one to put on his forecourt, than find new panels. Old motor ends up in a flooded quarry, minus bonnet, wings, boot, audio, alloys.....
Maybe I just watch too many episodes of Cop Wars Camera Action Zero Tolerance for my own good