There are zero situations in which trans people have attacked anyone in a bathroom. If we can't trust straight cisgender men to behave, then we should be policing and punishing them, not everyone else.
All of this is that fear mongering and legislation against transgender people using bathrooms has zero actual benefit, and many clearly understood consequences that affect both transgender and cisgender people.
I know there are many places that have unisex bathrooms now, so women can blame men. NO, it's not men hosing down the stall, trust me. My husband actually was appalled to think men were too lazy to even lift the seat. Then I told him it probably wasn't the men who made that disgusting mess.
As a frequent traveler through life and space, I often have the need to use a restroom in an airport. Such necessary actions require tenacity, humility, and tolerance, human attributes that may not eagerly spring into action after sitting four hours on a plane with a middle-age bladder.
The tribalism of organizing the world into categories comes from a very basic place to identify those around us. There are those that are men, those that are women and there are those that are not. Having the wisdom to know when it matters is what will make the world a better place.
Where did strangers answer the "call of nature" in Victorian London? At the start of Victoria's reign, options were limited. Some pubs had primitive outdoor "urinals" -- no more than a vertical slab of stone -- but men largely resorted to the nearest alley.
When I was a kid I didn't want money. I didn't want to be a VP at a company, like all my friends' parents were. I wanted to fly into outerspace. Or be a hobbit. Everywhere I looked I saw opportunities for magic.