I’ve also repeatedly been asked to sign one of those electronic signature pads as the signature to a document that I am not actually seeing. Which is a ridiculous thing to even consider as a workflow. When that happens I just sign the words “not shown document” instead of my name and move on.
Which they will the decline to sign and require you instead to sign there standard, cleared-by-their-legal consent to treatment form before providing any services.
If you could afford the kind of providers that would be willing to even consider a nonstandard agreement, this probably wouldn't be a concern you would have in the first place.