FBinNY 

Keep in mind that these asymmetry here.

None of those who chose not to wear helmets is making any effort to interfere with anyone's right to wear a helmet if they prefer.

OTOH, the reverse isn't true. There is a decent size contingent that would advocate making them mandatory, and another who while they wouldn't advocate for mandatory use, wouldn't speak against that because they already wear helmets, and so are unaffected. Then there's all the people who don't ride bicycles at all, and figure why not, it's gotta be good.

That's the problem with "apple pie" laws. They pass because they have narrow based pressure groups promoting them, and a large number of go alongs who aren't affected anyway. Unless we accept the principle of small government as a good in it's own right, narrow based laws will always pass.