At 20-30% off you are paying only 70-80% markup. The 10% off guy is getting 90% markup. No restaurant would create something like this if they weren't marking up the menu to start with.
You don't think about how much extra you are paying because you are too busy thinking about the discount you got squeezing yourself through a sign.
My mom asked me if she could lend my copy of Office Space to someone at work. She worked in a telecommunications office. It got around to everyone on her floor before I got it back. They had to do TPS reports so that movie hit really home for all of them.
I have never worked in an office like that and I hope I never do.