Actually I do remember the protests when seat belts became compulsory, the queues for certificates from doctors etc. There is now no medical condition which will automatically exempt you, and if you are not wearing a seat belt, you may well invalidate your insurance.
Perhaps if the insurance companies cotton on (excuse unintended pun!) and refuse to pay out life insurance to someone who entered a shop without a mask and caught it, then some might think again. Though sadly the reason for wearing them is unselfishly wishing to protect others rather than yourself, and some people don't do unselfish.
I understand that at the moment the risk of encountering someone with CV-19 in a shop is 1:3000. It is minimal, but I guess you would hope that that 1 person in 3000 was wearing a mask!