If they're going to have "express" lanes, then they should adhere to the guidelines. However......my resolution has always been this....just like banks used to use in the lobby....ONE line. Period. One line feeding the checkout area, no matter how many registers are open. As any given checkout becomes available the next person in line goes to it. No penalty for picking the line with the slow cashier, or the line with the person who cannot, after looking 5 times, find the credit card they want to use. Everybody gets the same odds and chances. When an additional checkout opens, everyone gains the same advantage as the single line moves quicker. If someone with 10 items wants special treatment, let them go to the corner convenience store and pay the high prices. Why should someone spending $25 get better/faster service than my wife who is spending $150.00?
Seems just obvious to me, but no one does it. I suppose the appearance of 30 people in line would just send some people to the exits, even if the line was moving well.