Not only is whether someone gives consent sometimes unclear, it's also unclear if the consent was informed consent and whether it was uncoerced.
Informed consent is obliquely mentioned in my other comment. For example, a patient may falsely believe their illness is terminal.
I realize I replied to a question about financial incentives to talk about non-financial incentives. But coerced consent would often fall under the financial incentive heading. E.g. "consent to be euthanized or I'll contest the will."
Forced "suicide" also has a long history, including in the ancient world. Arguably things like kamikaze might fall into that category. And it's a favorite method of execution in financial and espionage type cases because the method of coercion won't show up in the forensics.
For these sorts of reasons, I think the risk of mistakes is high.