I agree that projects like OpenCV should be better-supported.
There are a couple of issues, though, that always crop up, when talking about supporting open projects:
1) I don't know of any corporation, anywhere, that actually donates for no reason at all. There's always a hook. Sometimes, it's just brand-building (logo on the free swag stuff), sometimes, it's to attract future employees (for instance, donating to a project that is maintained by a certain set of students from a college curriculum, etc.), sometimes, it's to influence "hearts and minds," and sometimes, it's a pure investment. They need a self-interested reason.
2) I don't know of any corporation, anywhere, that donates, with no expectation of influence. That's one reason why lobbying is such a big deal. There's a fig leaf of "no quid pro quo," but everyone knows that the donator is expecting a return.
3) I don't know if anyone has noticed (</s>), but the corporate environment tends to be, just a bit, on the competitive side. I know many corporations may not be willing to donate to a cause that will serve their competitors, as well as themselves.
I think that foundations help. They can set up a "step and repeat" page, with donors, but keep the branding (and influence) off the actual donations.