Initial discovery research is pretty much entirely tax payer funded. There's then a second phase, moving from that discovery to POC, that is extremely underfunded, and which a lot of charity and such funding goes toward. It's only the last phase, taking POCs -> product, that companies really invest in. https://www.ncbi.nlm.nih.gov/books/NBK50972/

Now, that capital investment is not a trivial amount of money (about 80 billion in 2018 - https://www.statista.com/statistics/265085/research-and-deve... ), but it still is only 17% of drug company revenues - https://www.investopedia.com/ask/answers/060115/how-much-dru...

Note, too, that private companies tend to fund research toward common first world diseases, since they're profit driven, and far less to niche and/or common third world diseases. So not only do they not fund early discovery (government does that), nor generally moving those discoveries to POCs ('valley of death', and charitable foundations and the like do that), they also leave plenty of potential meds untouched, since the likely profitability is low.

Republicans would be hesitant due to “regulations bad,” and Democrats don’t want to improve our current system because they’d rather throw it out. And of course both sides get donations from pharma.