I used to go out to eat with my Egyptian friend & he never tipped. Sometimes I'd tip a little more on his behalf, then chew him out about it. It was kind of embarrassing.
This guy went out on a semi-regular basis, often times to the same places.
Sushi several times a week type shit. I just couldn't keep up with him, without going broke or getting fat myself.
He said they didn't tip where he came from, that he never tipped before & sees no reason to start now.
He eventually got a steady girlfriend who got it through to him.