I have a pet theory. If a workplace has a sign up that says something along this lines of "our staff deserve respect, anyone being horrible to them will be prosecuted" is usually guilty of causing the general public to get riled. It's not an excuse for violence, by the way, but it does rather encourage rather than confront a staff culture of contempt for the customer.
This was discussed at lunch on Monday with a regular traveller through Manchester Airport who agrees with me that it is a horrible place. When they lost our buggy a couple of years ago the self righteous "not my problem" attitude of the staff highlighted this. There was also a sign, as described.