It's apparently an issue which largely ended in the US. Congress requires TSA to report the number of individuals opting out for non-medical reasons (although you don't have to state a reason and if you don't, it's treated as a non-medical reason) and the number of opt outs at US checkpoints has dropped radically.

That may well be due to Pre-Check, but whatever the reason, it's a rarity. I remember seeing the 2016 numbers and now can't find them.