Many people sick with COVID are not getting this "standard of care" you suggest exists. Just tylenol and good luck. So those other drugs are not very far from ivermectin in terms of accessibility. All effective drugs are controlled and access is not given to the broad public, only to doctors and pharmacists, and many of these gatekeepers keep them from the sick people. You have to be lucky and have a good doctor who cares about you, not just about following what government agencies tell him to do. Then he may give both "unproblematic" stuff like heparines and also more "controversial" stuff like ivermectin.
The FDA regulates the marketing of drugs, not the practice of medicine. Physicians can prescribe whatever they want. Treatment guidelines are determined entirely by practicing physicians.
Uptodate is a good resource to check out if you want to see for yourself what clinical guidelines look like, and the type of evidence they are supported by.
https://www.uptodate.com/contents/covid-19-management-in-hos...
So why are THEY for these but against ivermectin?
Of course the whole idea of THEY is nutty. The idea that there is this level of coordination / cooperation among pharma companies is ridiculous enough to be the punchline of a joke.