Wouldn't work if you're using a bike share.

It's actually the reason why I don't use the bike share program, even though I have a station right next to my apartment building. I could ride it to/from the train station or the grocery store, but I'm paranoid about not wearing a helmet, and hauling the bulky thing around all day is a massive inconvenience.

Would you be ok with a mandatory helmet law for car drivers and passengers? The risk of a head injury that a helmet would prevent is much higher in a car, and carrying a helmet around in your car is more convenient than on your bike (e.g. it's much less likely to get stolen). Nevertheless, we don't have mandatory helmet laws for people in cars; why is that?

Locking it to the bike isn't a good solution if you live in a place where it rains or snows a lot. So you end up having to carry it with you on errands. If you bike a lot, those small inconveniences add up.

I can't imagine fashion sense is much of a reason, that seems like a strawman argument commonly conjured up by helmet laws advocates.

People being afraid their bike helmets make them look like goobers, maybe?

Well, they do. Better to be a goober with an unfractured skull, though.

I always thought the statistic that mandatory helmets reduced cycling was a bit pathetic myself. It really isn't that hard. Yes, I have come off my bike and hit my head, while wearing a helmet. Unfortunately, I landed on a tooth rather than my helmet, which wasn't a lot of fun.

Regarding helmet hair, I had a colleague who had the most amazing hair spikes (think coffee cup sized), who would very carefully put a cycle helmet on every day before cycling home.