I did pay it. I thought it was ridiculous to pay for a seat that should be for free given that it's going to be empty if a non-rev doesn't sit there. I'm fine with paying a fee for business class (United). But for Delta regionals we had to pay the fee even to just jumpseat due to how the system worked.

Anywho, you guys are missing the point entirely. My point was that some carriers charge fees (Delta), some require cleaning (JetBlue). Personally, I prefer to straighten a few seat belts as a courtesy to the crew that carried me rather than pay the corporation any money for flying in a seat that would be empty anyway. But that's just me.