De Facto describes situations that exist in reality (in fact), even if they are not legally recognised. Sundown towns exist in reality regardless of the law, and non-whites driving through them can face harassment and even arrest or prosecution for no other reason than being non-white while driving. The reason given for the arrest or prosecution will be a book crime, but that's not the actual factual (de facto) reason for it happening.

> How many non-white Americans get sentenced merely because of driving?

Arresting non-white Americans merely for driving isn't de jure but your question presuppose that it is or that someone her is claiming that it is(nobody is). Can't get any more obvious that you are mixing de jure and de facto.