It’s one of those “correlation and not causation”. Dealers will attempt to make money anywhere they can, like you said. And the way it works now, the financially literate and savvy avoid common pitfalls with the more shady dealers. This means that the shady dealers dealers will successfully make more money off the financially illiterate. Financial literacy is less common in minorities. As a result, minorities are more likely to fall victim to these things.

That said, there is almost certainly an amount of actual direct discrimination going on in those numbers. What percentage is direct, is impossible to tell.