And easily dismissed when the defendant says "we showed him the document when he signed it. We show it to everyone" and now the onus is on prosecution to prove it.
The onus is not on the one who says it the loudest, it's on the one who can provide proof. The defense can explain to the judge that they turn the screen to show it or whatever it's supposed to do.
A contract signed under duress is not a valid contract.
There's no reason that the provider's testimony is magically preferred over the patient's, and in fact the generaly pratice is to resolve ambiguities in favor of the person who did not write the contract and is not the professional who has had plenty of pratice to know what they should be doing.
The onus is not on the one who says it the loudest, it's on the one who can provide proof. The defense can explain to the judge that they turn the screen to show it or whatever it's supposed to do.