It’s mandatory everywhere in Europe (the plate looks Spanish I think), and in some US states.
Dunno which other countries don’t require a front plate, but it’s not very common. Some Asian countries even require a front plate on motorcycles, which is about as aerodynamic as you can imagine.
On cars tho I don’t get the obsession with removing the front plate, it’s fugly on 99% of cars because there’s a flat spot anyway. But in my experience Americans are very enthusiastic about their ugly front bumpers, so you do you I guess.