I'm willing to admit the possibility, but I'd like to point out that half your examples are commercial products. There's a big difference in my mind between "get paid to work for someone on a product" and "volunteer your time for someone on a free project".

In particular, most business people I've worked for have been, well, let's say 'ruthless', even with their own employees. If I'm going to work at a company, I don't feel I have a lot of choice here. Most open-source maintainers are nice and reasonable (perhaps out of necessity), so if I'm donating open-source patches, I do have a choice there.