There are many problems here... from monetary (all the pharmaceutical companies want a new, expensive drug, and not something old and cheap), to political (who wan't to deal with another experimental drug, after all the contraversy about the others), to political2 (who want's to be a antivax hero, cited by all the virus deniers), to risky (whatever you publish, all of your previous and future work will be scuritinized by everyone, and one small rounding mistake ina paper you wrote 20 years ago might destroy your career), etc.

It's a lot easier to work on AnotherCure(TM) for baldness, than touch this pile of political crap.

That sounds like it works like that, but that is not always the case. They do try out promising could be medicines, especially since Covid costs enough as-is.

Can this system be improved? Definitely.