The Basic Med exam is done to FAA Standards. Just different ones.
And like your annual, the doctor is only liable until you get out the door. And even then, it would have to have been an issue that he/she should have seen with in the parameters of the exam requirements.
Does your doctor guarantee that you will have no problems after you have a normal physical exam?
A class 1/2/3 FAA medical references a giant book of medical standards for AMEs, with a big list of what passes and what fails. Have high blood pressure? Have a stroke while flying? The AME can point to the big AME book and say "look, the blood pressure was within the limits on the big AME book, treated with medications on the approved list, so I checked the box the FAA told me to check, and they got their medical."
The BasicMed form, on the other hand, ends with the doctor signing a statement that says "I certify that I am not aware of any medical condition that, as presently treated, could interfere with the individual's ability to safely operate an aircraft."
"Could" is a hugely worrisome word here. The statement doesn't say "I don't think this person is any more likely than the next person to crash an airplane" or even "I don't think this person is any more likely than someone with a class 3 medical to crash an airplane." It says "I am not aware of any condition that
could interfere."
Switch to the courtroom scene. "Didn't you know this person had high blood pressure?" "Well, yes." "And didn't they teach you in medical school that high blood pressure makes strokes and heart attacks more likely?" "Of course." "So why did you say you didn't know of any condition that
could interfere with operating an aircraft?"
I don't think there
should be higher liability for BasicMed sign-offs compared to FAA medicals. But the way our legal system works, only time will tell, and it probably won't tell us very publicly. As a physician, it would take a hell of a lot to convince me to sign off on people who I didn't have an established doctor-patient relationship with, and even then, I would need an insurance company to specifically look at that form and say "yes, you can sign this and we'll cover you if there's fallout."
I am not at all happy that that's how the world works, but it is.