There’s no collusion if they’re all owned by the same vendor, which is common (and pointed out in TFA). The problem then isn’t collusion; it’s that the agencies responsible for ensuring fair airport pricing are captured by the businesses that they’re supposed to regulate.

Sounds typical. Not an airport specific problem

Like entiries with like goals will conduct themselve similarly. The market defines what it will bear. They don't need to collude.

> (I usually bring an empty with me but not the point)

I’ve been in airports where the toilets behind security have ‘courtesy’ warm water at the faucets

Go to any airport an Asia and you will find plenty of drinking water fountains. Sure, sometimes the cold water is broken but at least it's sanitary drinking water.

Meanwhile Frankfurt tells you that the tap water in the restrooms is safe to drink. Absolutely absurd that Airports where you are effectively stuck for possibly hours and are paying for that priviledge can get away with not having to provide basic neccessities.

No it's not.