Not that I particularly preach this myself, but it isn't hard for me to see how taking it on and off and carrying it around or stashing it as you go about your daily activities is a bit more tedious than clicking in and out of a seatbelt that never leaves your car. Did it on my motorcycle, and it just is not fun having the thing sitting on tables, on the bar top, in your hand as you're walking through a store, sitting out hoping it doesn't get stolen, popping the seat off to store it on the motorcycle helmet mount, etc.

The folks I talked to in the Netherlands also told me every few years a mandatory helmet law comes up for debate, and is almost immediately scrapped because of fears that large numbers of people will quit riding if they are forced to wear a helmet. The gov't sees far more health and infrastructure benefits from a public that largely cycles than saving a few dozen lives by mandating the helmet. Short of the elderly and group riders on go-fast bikes, people simply do not wear them there. Maybe someday it'll catch on, I doubt it. Seatbelt usage never really got high here until it was mandated and tickets started getting handed out (and some of haven't even learned our lesson even with a couple of those )