These things are self locking, so you release it as soon as you leave it unattended and are not liable anymore. If you had to look for a docking station, it would be not practical.

How does zipcar handle car theft?

Zipcar buys insurance and GPS/cellular tracking devices.

Nobody who bikes regularly or serious owns a $100 bike. Good bikes start at around $1500, which is why bikes are such frequent targets for theft.

Sounds like a No True Scotsman fallacy to me. I've commuted daily for years, plus occasional longer trips, on a used bike that cost $150 (plus another $100 to add lock, rear rack, fenders and lights). Maintenance may be a little bit more with a used bike, but it rides great.

My $400 bike does me well enough.