I had to use a public toilet yesterday, here in Cape Town, South Africa....local mall situation.
While you may not be aware of it, the Cape has had three years of drought, and recent rains have marginally refilled the water supply. So everywhere you go, there are signs about not wasting water....your daily limit is 70 liters.
So I walk into the toilet and here is a 'cap' on the lid and some note about 3,000 pounds of air pressure. I do my business, lower the cap, and hit the button. A cup of water drops down, and BOOM, some massive air pressure event occurs, and whatever was there is gone.
If you'd been sitting there? I think some bodily damage would have been done. It's something that would never be allowed in the US, I think.
The engineer who designed this? Just makes you wonder about the testing phase.