Firstly, thank you - from a personal point of view, your answer is very re-assuring. I check my blood pressure at home every day, and I am always fine. I get to the hospital, and it's white coat syndrome, but never past 160.
Yes, they seem to get you to sign a waiver for most things. Bangkok Hospital did the same before each of my operations. However, at both hospitals they undertake pre-ops, and if there's anything remotely wrong, they won't proceed. This is the same as the UK.
My point is (and it could well be the press glossing it up), if they had found something that would put me in 'danger', they would have found an alternative treatment or cancelled the procedure. I would hope if they had identified a danger, they would not have vaccinated the lady, waiver or no waiver.