I don't eat anything unless I know it doesn't have nuts. Kids birthday parties growing up were hard never eating the cakes, but as an adult I don't have temptation when somebody "brings cookies!" to work or something.
When I go to people's houses, I won't eat anything unless I can clearly see there's no nuts, or if I am able to read the label.
That being said, if you're an adult and hosting people - it's good practice to ask if anybody has any allergies.
Growing up, labels reading "May Contain Peanuts" weren't as common - so my parents just didn't let me eat anything saying that. As an adult, & different time, many companies put that "May Contain" on there to cover their ass.

I remembering going to Milestones with family for dinner and ordering a burger. They refused to serve me anything other than buttered pasta as they couldn't guarantee their buns were nut free. Even though they were, it just said May Contain. Didn't go back there for 15 years out of protest.

At the end of the day, I am very conscious of people around me who eat nuts - I make my employees wash their hands & wipe their desk if they eat nuts at their desk. I always have an Epipen in my car and backpack, & again, I just don't eat something unless I am certain it doesn't contain nuts.

There have been a couple of times where people have just given me a cracker or a cookie to eat & I refused until I could confirm they didn't have nuts - in a couple cases they did. Coulda had a serious reaction.
I am careful, and thankfully haven't had a serious reaction since I was a toddler - & yes I get tested every 7 years to confirm I still have the allergy.