Out of curiosity, do you know how many people opt not to get them? USA has a growing prevalence of vaccine hesitancy/anti science that gets concentrated amongst regions/social groups. It’s an issue IMO because you get areas with low herd immunity, but if we didn’t have that problem and the vast majority of people were on board then having them be voluntary wouldn’t be an issue to me. In the current state of affairs I think it’s too dangerous to have them be voluntary in the USA.