The free market really has no method of pricing developments with 30+ years to profit/free cash flow. The government first started subsidizing solar to be price competitive in specific situations in the 1970s.

There simply aren't any rational free market actors funding large unprofitable initiatives for 40 years with the expectation that the technology will be a bananza after all the principals have retired or are dead.

Exactly, private market r&d dollars chase a local maximum that influenced by the length of patent laws.

Isn’t the damage to climate and health arguably a subsidy to big oil? While they get that damage for free, of course they win.

Actually, they wouldn't win; many renewables are cheaper than fossil fuels nowadays. Though this is a good point; we need to factor “stealing from the future” and other externalities into the price somehow, if we are to use a capitalist market. (Hence carbon taxes, rather than carbon subsidies, should be government policy.)