If you have ever worked in any form of customer service job, you would know they are some of the hardest jobs to work in...i don't care if you're getting paid minimum wage or getting a good salary...if you deal with people all day long, your patience wears thin eventually...
I'm not excusing bad or rude behavior, but you can tolerate people more if you've been in their shoes
Same goes with waiters/waitresses...everyone should have to work a few months being one so they understand what it's like and aren't assholes when it takes a minute too long to get their drinks (or whatever) when they go out to eat
What happens here, stays here