The statement, "Some stereotypes are based in reality," is very ambiguous. Hard to falsify what you're saying there.

What the above parent wrote is, "there's no good reason for black people to give cab drivers a hard time." This implies that, given that there's not a good reason, it is not likely true.

So, what do you think the reason would be that black people would unanimously give this cab driver a hard time, except for this one guy? Based upon your above proposition, you may also want to explain why your explanation is not racist.