I have a nut allergy. A very serious one. I can have a reaction from touching someone, who has touched nuts. Mine was less extreme when I was young, but each reaction does get worse...which is why I think it's so much worse now.
There are no nut free places, as adults. However, I am more equipped to be very careful. I wipe down tables before I sit down. I call around look online, and only eat at restaurants that serve no dishes with nuts. (I pretty much can't eat Asian food.) I pay attention to what those around me are eating. If I see someone with a granola bar, trail mix, pb&j, chocolate...I simply move away from them. If I am eating at someone's house, I do inform them of my allergy. I stay completely out of other kitchens. I don't go to stores, when they have sample days. (In case, the samples are something involving nuts.) I read every label of every food item I am exposed to. If I am at a park, zoo, (or a place with lots of kiddos) I do not eat near any children or touch anything. I don't go to functions at schools, unless I know the school is nut free. I don't have my son in daycare. Obviously, I always have an epipen. These are all things, that I was not able to do as a child. This is why I support nut-free schools when needed. Kids don't have the capacity to look for nut contamination in all the places and ways, that can be very dangerous. Other children are not good at washing up, thoroughly. I was NEVER a risk to myself as a child, it was everyone else. By middle school and high school, I was fine. I could use my epipen and I was mature enough to handle all the ways I could have a reaction. As an elementary school kid, no way. I think it's only necessary to have nut free elementary schools. (When needed.)
As for the prevalence, I have no idea.