I agree, but it is two separate events. The no-stamp thing is a rule, but not 100%. I have viajeros confiables, Mexico's version of GOES. I am a US citizen. There is no stamp, and honestly, the visa looks like it was printed out on a 1989 fax machine. Yet with a few hiccups when the program started, they accepted this when I was leaving the country. But they legally cannot let you board without a valid FMM. Same thing with the required interview sticker. They wont let you board a flight to the US without it.

The second part is what annoys me, and classifies as "evil". AM is cutthroat about its charges and boosting its revenue stream. I had a situation where I had a bag pulled at customs with a tight connection. I did not know this until I was already in line to board (the bag was supposed to go straight through). So I had to go though a bunch of hoops to get back to my bag, submit to search, and then recheck my bag. Obviously I missed my flight, and I know it was not AMs fault. Not only did AM want to charge me 200, they gave me a ton of crap about missing my flight. The first response I got was "you missed your flight, it's not our problem, you need to book a new ticket."

I got lucky, as I had Platinum Status, a full fare business class ticket and zero patience for BS after what I went through at customs. I did get the next flight without the change fee or flight price difference.