The point is they are not variables, but rather constants (everyone got them), and they were not introduced, but standard care at the time.

I suspect you have the wrong idea about how the results of the trial are supposed to be interpreted. The point isn't to compare to results outside the study. You should only compare the intervention group to the control group in the same study.

Because it's unethical to leave people who are sick with Covid-19 untreated, so they all got what were considered possibly effective treatments at the time.