I find this amazing. The TSA can not legally make anyone remove shoes (though they encourage it to speed up the process). At OAK this afternoon, I was wearing rubber shoes. TSA asked if I wanted to remove them. They added that the alternative is to go to secondary. So I decided not to remove them, and the TSA pulled me aside.
The guy who did my secondary was very interesting. He kept on saying, "You are being so cooperative. Most people yell at us for doing all this."
I said to him (with a light hearted laugh), "I'm just standing here, you're doing all the work!"
Anyway, I find it intersting that the punnishment for not removing shoes is secondary, even when the shoes don't set off the detector!