In Italy, a Bolognese sauce is a very simple sauce that uses the best ground beef (beef ground from the “worst” cuts, i.e. the cheapest meat with the highest intensity of flavor) cooked very slowly, often in a little milk. A bit of tomato in the sauce cuts the richness and provides a balance.
In America, this hamburger sauce becomes a riot of chopped vegetables, often very intensely flavored ones like bell peppers. Someone from Bologna would have a hard time recognizing its roots.
Odd, because in America the emphasis is usually on meat.
And the sauce is served with hand made Tagliatelle. Not spaghetti.