I know that whites cut in front of everyone. I worked in direct contact with the public for years and I cant recall other races doing the same thing.
I ended up inadvertently embarassing my boss and one of the other professors who taught at Bethune-Cookman College in Daytona Beach. We had gone out to lunch and were standing in line for the buffet when these two white women looked at us and then got in line in front of us. Being from southern California people just didn't behave that way so I very politely but pointedly said "excuse me, but we were next in line" indicating our group and then got in front of them. I was later admonished that I shouldn't have said anything to which I immediately replied "Why not? They could see us standing there and if they were mistaken thinking that they were next in line I corrected their misconception."
I don't think they ever saw things quite from my perspective at least not that I am aware of but this practice of ignoring black people who have been standing in line before them was very prevelant there. I also worked in a department store while in school and initially I would rely on the customers to do the right thing as far as determining who was next to be waited upon by asking "Who's next?" but the white women would inevitiably cut in front of the black girls & women standing in line. So I stopped doing it and if I saw one customer cut in front of the other I would say "No, she was next" and would direct the lying customer to get back in line. Again, only the white women were doing this because most of the black people down in Daytona Beach that I met and ran into were all very well mannered and polite. Some of the white women got pissed and left to find another cashier which was fine by me because I just sensed that management had enough sense than to tell me that the white customer had to be waited on before the black customers.
It wasn't much, but the looks of appreciation and the thank yous I got, particularly from the older women made me feel that it mattered to them.