I’m in the US and haven’t bought compressed air recently, but I definitely didn’t need to present ID the last time I did.
This article says 38 states have age restrictions, but after a brief search, I couldn’t find any evidence for this in my state (Utah). It’s illegal to use it to get high and to sell it to someone with the understanding that they’ll use it to get high. But now I’m curious, I’ll have to ask the next time I’m at a store that sells it.