One of the drawbacks of flying is that you're sharing the lavatory with a couple of hundred people of unknown hygiene standards, and the thing won't be properly cleaned again until the plane touches down.
Smaller operators claim that this is too heavy and expensive for their light aircraft.
So where Boeing's system is automatic, their solution is manual.
Oh, at first all the passengers laugh when we tell them how dedicated we are to keeping our limited facilities spotless.
But after we start ejecting people who leaves the lavatory dirty, we have no more problems.
