Does delta leave checking bags to gate attendants to decide? They really shouldn't.

Boarding a flight at zone 5 is usually pretty safe for avoiding getting my bag checked. However.

Leaving ATL recently, the gate attendant got to zone 5 and let everyone know they would be checking the first 20 bags in line. I was in the front of the line for zone 5, I moved to the back of the line for zone 5. I was bag number 20. So zone 6 didn't have to check a bag, but zone 5 did. I complained to gate attendant, but got the usual, I care about nothing response.

I fly delta exclusively. It seems really stupid to have different policies depending on the GA mood.