MM I think you answered your own question. Generic, cheap and the RX companies want it fail based on greed.
there numerous studies going on to finally answer the questions about effectiveness for inpatients, outpatient and as a preventative for medical folks. All meet the establishments requirements.
vitamin D seems to be key to prevent deaths from COVID. Sunshine only provides D during the summer, you have to supplement in the winter. Why not test that? It's cheap!
finally if you look at Germany COVID death autopsy data (required in Germany) the lungs weigh 3-4 times normal due to thrombosis (blood clots). Ventilators are useless and actually probably worse.
(bet if you ask Inpatient docs and RNs if they are taking the malaria drug with zinc, they will tell they are)
morale, get sunshine in summer, supplement daily with D 400 units, especially if you are a senior like me.