I don't think there is any evidence to say that doctors and scientists are any more susceptible to bribery than any other person. There are millions of doctors and scientists in this country. Are they all on the payroll? Of course not. Free pass away, unless you truly believe that one bad apple must sour the whole bunch.
I don't think people in those jobs are more susceptible to bribery, but the jobs themselves enable and support it. A person could bribe me at my job, but even if I took the money there is oversight and someone would see something was mishandled and I'd be quickly fired.
The systems in place to prevent doctors and scientists from taking money to push drugs or falsify data are failing us which is how companies regularly use scientists to get whatever results they want published and drug companies bribe doctors to prescribe harmful medications unnecessarily.
Anyone can be bribed, but not many of us could get away with it at the scale that brought us things like the opioid crises and few of us have literal lives at stake when we are tempted to act unethically.
