> This is a result of a strange pricing algorithm mistakes, right? Surely this doesn't maximize profit.

The Saturday night stay rule is alive and well in certain markets. Business travellers like to be safely back home before the weekend, and their [employer's] pockets are deeper than leisure travellers.

The average leisure traveler typically isn’t taking a two-day international trip. Airlines see an opportunity to extract more profit from business travelers who may not know their return date. A significant example is Lufthansa (and co) — multiple thousands of dollars to book a one way to Europe, under 800 for round trip.

I wonder if they don’t intend to offer one-ways at all, but are legally required to publish the tariffed pricing that nobody actually takes.

Another example here is how much cheaper round trip tickets get when they cover a Saturday night.