That's because most of us recognize that 20 seconds with angle grinder will make that $1,000 bicycle disappear. 20 minutes at a stolen bike dealer - which are everywhere - will turn it into $50.
20 seconds with an angle grinder will not make a $30,000 car disappear. Selling it on the black market is also a much bigger pain in the ass, then selling a stolen bicycle.
People leave $300,000 dollar homes unattended all the time - protected by nothing more then a flimsy lock, and a few panes of glass. Yet, most of the time, people don't worry about someone stealing their house.