I do think there is this type of attitude among blacks sometimes but I think it's up to the larger white lady to put them in their place and refuse. If there is a chance of violence as a result of the refusal, I have read several suggestions posted before.
One of them is to give them a number to another location, like a restaurant or the police station. Another suggestion is to tell them you have a boyfriend (Even if you don't), and his name is Thor.