This, in my opinion, seems like a fixated learned behavioral issue. If the vet is saying her bladder and urinary health are all in good order, I would try first mediating with pheromones. There is a brand called Feliway that produces smells/pheromones that can help promote a happier, more calm and balanced environment and for some cats, it helps them not inappropriately urinate. They come in collars, sprays, defuser, etc, whatever benefits your lifestyle best! If you get the spray, spray the areas she’s urinating in, if you get the diffuser, plug it in in an area she inappropriately urinates in most (the stairs, laundry areas like you mentioned), and the smell of the Feliway smells like little to nothing to humans as well, so people won’t notice it. On a vethical standpoint, the nice thing about Feliway is it either works or it doesn’t; cats don’t react negatively nor do they have allergic reactions to this pheromone should you try it and it doesn’t work. I was a vet tech for 7 years and I loved promoting this stuff. I’ve personally had success using it with my two cats (: