That's interesting and you do wonder why these countries don't have better standards its not like work hasn't been done on this.
I used to work in hydrodynamics R&D (BHRA / BHR Group) and I shared an office with an engineer who had a project to analyse the UK's toilet designs and come up with design guidance for more efficient designs.
It was interesting to listen in on the call to the plumbing supplies company when he wanted to buy a couple of hundred toilets but instead of 200 of one type he wanted 2 of every model they had.
I did look at Computer vison / ML for this project, to measure flushing efficieny - but it was to expensive
I used to work in hydrodynamics R&D (BHRA / BHR Group) and I shared an office with an engineer who had a project to analyse the UK's toilet designs and come up with design guidance for more efficient designs.
It was interesting to listen in on the call to the plumbing supplies company when he wanted to buy a couple of hundred toilets but instead of 200 of one type he wanted 2 of every model they had.
I did look at Computer vison / ML for this project, to measure flushing efficieny - but it was to expensive