Your statement doesn't make any sense. A quick search of LinkedIn shows:
2,798 results for capital one software engineer
It's a company with a $50bn market cap, and ostensibly stable 9-5 employment. This is more of a symptom of having a ton of different products where people weren't interested or weren't able to create a unified login system.
Chalk it up to 'bad' engineering practices if you want, but not that there's no one to work at these companies.
This is so, so very wrong - Capital One is crawling with software engineers, they're considered way ahead of most other FIs with what they're doing. The history of Capital One is why this happened - it has acquired so many things and grown horizontally so quickly that they're struggling to catch up.
Chalk it up to 'bad' engineering practices if you want, but not that there's no one to work at these companies.