Yes, people lock their bikes: they all have that built in wheel lock thing. It's not like it's a perfect utopia. People are actually very careful about that. Nobody rides around with the giant NYC-style bolt-cutter proof chain like a belt though. You couldn't even have a $1000 bike in NYC but you see them all the time here. There is definitely some theft and crime but it's definitely less.
Also, the biggest bike thief is probably the city. ;-)
A bit of an exaggeration on 'you couldn't even have a $1000 bike in NYC'. I have one and lock it up outside - I see plenty of them locked up around town. But, yes, they're all locked with thick chains and heavy locks, and the seat should be locked to the frame as well if you want to keep that too. Having renters insurance is good too since that will cover you if your bike is stolen.
I agree. I'm actually glad bycicle theft is just about the worst crime that can happen to me.
Wait, you live in Tokyo, don't you? (I think we met at one of the meetups)
Everybody locks their bikes here, and even so bycicle theft is common (well, at least compared to the other types of crime). My own bycicle was stolen while I was out of the country for a couple of weeks...
That said, I understand that's not the main point of your comment.