Why does Oliver say he pays Ven the same as Char?

Oliver invites Char to sail with him on any vessel before paying him and Ven the same wage Ven protests, but Oliver insists. He explains that Char actually has an easier time coming, as he is human, and Ven is not. He reminds Ven that some people in town will not accept him, nor serve him, as a result of his race.