About strictly enforcing boarding order I wrote in a recent post.

Where it descended into absolute chaos was the flight to Frankfurt. First class, business, and priority passengers (mothers with children, passengers with disabilities,...) had their own gate. The rest of the plane (economy and premium economy) shared one. Since the aircraft was only connected by one jetbridge, it would have made perfect sense to board the front section passengers first through the second gate — they'd just walk through the back and not block anyone. Wrong. The agent kept sending back everyone who didn't belong in the rear rows. The queue was also single file only, splitting off only at the flight attendant who scanned you through. Chaos upon chaos... Luckily we made our departure window and avoided the storms.