If it became common knowledge that you can arrive at airports earlier, and people started acting on it, then travelers would notice the new equilibrium and adjust, and on net it would still be positive since people would spend slightly less time waiting at the airport on average. I don't see how this is defecting - it feels no different than how people change their commute patterns when a new road opens, no?

Also that advice was aimed at frequent flyers for whom missing a flight isn't a huge deal. For the average flyer it still make sense to arrive early to leave generous margin for delays, which the post acknowledges

imagine that someone in the shop's decision chain realized that if their food never makes their customers sick, they are spending too much money making sure that their food is okay."

This is basically how things work and also seems fine? If you wanted to absolutely minimize food poisoning you'd prepare food in a BSL-4 facility, which nobody asks for because it would be ruinously expensive.

How sure are you that making your favorite product worse in any possible dimension is something you would immediately find out and punish by changing your supplier?

This feels overly focused on one direction of change. What I observe at the grocery store is some suppliers make changes that make the product worse and offer me a lower price, while others make their products better (low sugar options, higher protein, ethically sourced ingredients...) and offer a higher price, and the market sorts out which changes which people want

"If you have never betrayed your customer in a way they would be shocked to find out..." complete the pattern. If ethics means anything, it means leaving the money on the table sometimes.

I agree being naively utilitarian and betraying your customers' expectations is bad ethically, but it's also bad for the bottom line. Brand reputation concerns and competition from other suppliers (who will loudly tell customers where they have higher standards than the competitor) keeps it in check