My guess would be, that MSRC and Apple's equivalent have an OKR about keeping bounties under a certain level. Security is seen as a cost centre by most companies, and what do "well run" companies do with cost centres... they minimize them :)
I don't think that organizationally either company wants to have bad security, and I don't think that individual staff in those companies want to have bad security, but I do think that incentive structures have been set-up in a way that leads to this kind of problem.
I've seen this described as lack of resources in the affected teams, but realistically these companies have effectively limitless resources, it's that they're not assigning them to these areas.