In Japan, heart surgeon. Number one. Steady hand. One day, Yakuza boss need new heart. I do operation. But, mistake! Yakuza boss die! Yakuza very mad. I hide in fishing boat, come to America. No english, no food, no money.

This is non-ironically the best possible explanation to how Mario is can be a legitimate doctor.

To be fair a plumber in Brooklyn probably makes more money than a doctor

Why is it bad to be a plumber

That’s funny but it’s actually terrible that this happens a ton in America