> Denial of Shitter attacks are always unethical.

Here in Germany, the railway itself is the worst culprit - in December, when DB took over the notorious Hof-Munich line, I travelled on a 6-car double decker train that had 5 broken toilets, all of them because either the water was out or the sewage tank full. Not fun.

The second worst culprits are idiots throwing trash into the toilet. Diapers, tampons and wet wipes don't belong into regular toilets - but especially not into vacuum toilets like on trains or planes.