The ones I say explicitly say that you're signature acknowledges that you've read the policy. You have to ask to see it before signing. It feels skeevy to me to be sure but honestly it's not all that different from signing something you have been given but still haven't read.
Edit to add: also, I've seen this in more places than just health care.
Nope. No verbal or written statement about a written policy being read or existing. I don't know what happens if you demand to see one, but one isn't offered at all. There's no fine print on the display saying you have read anything. It's just verbally "sign for this" and you do. Yet they don't condense it down to one signature.
I complained and was ignored in the same way people are ignored when they complain about the wait in the ER or ask how much treatment will cost.
Edit to add: also, I've seen this in more places than just health care.