You could view the bounty prices as market evidence that most of this is rightfully treated as nothingburgers. I.e. the alternative to paying $5000 to some random person for this class of vulnerability research is not risking a trillion dollar hack the next day - it's just risking shmaybe some kerfuffle down the line, followed by fixing it through normal triage process. The bounty program is as much marketing as security, and $5000 is probably about the right price for marginal effort into sustaining the "we are treating security seriously" message.
In a way, the very existence of those bug bounty programs in large companies is evidence they don't see a reason to treat vulnerabilities seriously enough to proactively find and fix them in-house.
If security vulnerabilities would be anywhere serious as most commenters on-line seem to think, companies would pay hundreds of thousands for serious vulnerabilities, just to save a day before they get hit by them - on top of spending millions in-house to try and stay ahead of the attackers.
But they don't. Because most exploits are inconsequential and/or aren't being exploited much.