I don't think laws are the reason people are not transacting with Bitcoin more. It's hard money that's expected (by those who hold it) to appreciate in the future.

Merchant adoption will come when Merchants actually demand Bitcoin, either by giving discounts for those paying in bitcoin, or not accepting fiat. Bitcoin and Lightning UX is only a part of this. The greater factor (IMO) is Gresham's Law and the use cases that only bitcoin can serve and fiat cannot.