Why doctors are afraid to write medical exemptions
... even in life or death cases, for masks and vaccines.
They could lose their license to practice medicine -- not lose their job, lose their license.
So if you were allergic to ingredients in the vaccine or had a breathing issue that prevented you from functioning with a mask, a doctor in certain states will not write you the exemption you need.
We have to understand that mandates are a public measure that takes no account of individual needs, much less the right of each person to determine the measures he is willing to take, especially to prevent an illness he doesn't have. (For more on bodily autonomy and how vaccine mandates have worked in the past, go here.)