So, the PHP unit has a lot of stuff about tipping calculators, and as somebody from a country where tipping isn’t done (we just pay wait-staff a living wage), it was one of the biggest screeching roadblocks in the entire unit.
I’m sure Americans can do that sort of math handily on the fly, but if you’ve never done it before it’s a huge pain in the ■■■. It’s just not a daily calculation we have to make. It’s not necessarily that it’s difficult, it’s that it doesn’t come naturally and it bogs everything down. Lots of developers aren’t from the United States, but these questions are built for US users—a question that’s a bit less culturally-locked will probably go down a lot more smoothly.