This is one of my concerns, 10 years ago we had to have a new kitchen ceiling where the previous shower cubicle had leaked,
My concern wasn't so much the cubicle, which after all, is simply a shallow bath, even if it's the full floor, it was more the pipework underneath in the event a joint or something fails. At least with a bath, you can take a side panel off, but with a walk in shower, once the floor/base is down, you're pretty much living on hope, especially upstairs.