Forgiveness answer: At least for me, hearing someone speak in a foreign language near me if I’m trying to do something is like Kryptonite for my concentration. I basically just have to leave and go somewhere else, or else abandon the idea of getting something done until it stops. It’s just impossible for my brain to not pay attention to it. I don’t think I would ever blame it on the person who’s just trying to have a conversation, and if I’m just standing in line or something it doesn’t bother me, but I do understand how it can be irritating.

Probably more realistic answer: Because living in America leads to a spiraling hell of stress and unhappiness, and so if you’re an asshole, and some innocent person presents themselves that you can take it all out on for literally any made up reason at all, then it’s go time. Also explains a lot of taking it out on customer service people for literally no reason at all.