Look at the characters in the movies where these comments were made. They're deplorable human beings that probably really think like this.

In Goodfellas, you got Henry Hill talking about the only people that go to jail are "nigger stick up men who fall asleep in the getaway car" and then later in the film you have, ironically, Stax Edwards driving the getaway car, fucking up the disposal of the car and Tommy killing him. Incidentally, in The Heist, a book based on Lufthansa, Stax and Tommy turned out to be childhood friends and it tore Tommy up to kill him, but they told him he'd probably be made on that murder.

Earlier in Goodfellas, you got the truck driver who, after Henry and Tommy stole his truck stormed into the diner declaring, "Two niggers stole my truck". That's how these guys were back then and are now. The racism in Scorsese movies is no worse than the average Tony Soprano racism.

It is present in most of his movies from Travis' racist undertones in Taxi Driver to the blatant and murderous racism in Gangs of New York, but that is the world these movies inhabit and that world is based in fact.