I think if you want these programs at all, you have to make difficult decisions. The fact is, nobody is going to carry a helmet around on the off chance they are going to use a rideshare. If they have one at all, they're using their own vehicle. I've used Seattle's bikeshares a few dozen times now, and I love it a great deal, but I never would've bothered if I had to wear a helmet - I would've just taken an Uber or something.

I have even seen some people claim that, measured in QALYs other such utilitarian metrics, helmet laws make people unhealthier on average in that they discourage riding bicycles and that the net effect of this is worse than the increased risk, but I don't know how reliable that result is.