Last comment and I will shut-up.
I understand vets/vet hospitals have no idea if a person will pay or not. However, if a person didn't pay... wouldn't they just go after them, like any bill collector would? I'm NOT saying that is the perfect scenario. Why isn't it assumed a person WILL pay, instead of won't?
I feel for your sister sooooo much. I would assume she was stressed to the max ...worried about her boy cat. If she knows anything about vets, she also had to wonder if the vet was being dishonest or up-selling some sort of BS. Top it off with demanding thousands of dollars up front. What a frickin nightmare!
She STILL ended up paying the full estimate... pretty much... and yet she had to bring her boy cat home in a box. I KNOW there are no guarantees. But when you hear stories like that, ALL the time... makes a person wonder.