Having lived in the US for 30+ years, eating out a lot all over the country, and working during college at a restaurant, I have to wonder where you are getting this idea. Would you care to explain?
It has been my experience too that other waitresses do not serve you. I'm in Boston and often when I get another waitresses' attention, instead of helping me they quickly rush off and signal that they will get my waitresses attention. Also, during peak hours waitresses are generally territorial. Once they've served you they expect you to order through them at all times. I've been told numerous times that I must order through them and not at the bar.
