With Galileo coming online, you can get sub-centimetre position resolution, which would enable you to clearly identify riders misplacing bikes.

In regards to bikes being picked up and moved, a simple alarm might help. But I really doubt that there would be much vandalism against parked bikes that don't get in the way. After all the streets are full of parked bikes, and vandalism is quite rare.

(Yes, I have seen plenty of bikes with parts missing or bent wheels. But these usually remain in place for years, based on my observations, skewing superficial impressions. I've parked my bike on public streets for years, and the only thing that ever happened was my fancy saddle once being stolen.)