I love ethnic foods. In fact, sometimes I prefer a good Thai dish to a ribeye, yet I won't shop at an ethnic market. I think they discriminate; They cater to their own and don't want my business. If they did, signs would be in English also.
The way they operate is a reflection of their culture and it may conflict with others. I've gone into a Hispanic market looking for a particular chili that I couldn't find elsewhere and felt like I was in another country. I found what I needed and couldn't get out of there fast enough. I think I was the only Gringo in there.