My experience has been two extremes:

1) companies that use open source, modify it (to the extent that it's largely proprietary), and deride the open source community that competes with them

2) companies that use open source to leverage non-core functionality they need... and move on with their real value-add

Companies in the style of (1) never contribute back. They see open source as the competition, even though they use it themselves. They don't understand that proprietary extensions are just that... proprietary software in a non-expertise area, that no one else in the world knows anything about. Instead, they spend more and more money "fixing" things which were already fixed in the upstream releases years ago.

Companies in the style of (2) contribute back minor bug fixes or features which are pain points for them. They sometimes pay for other people to write new features.

I say this as someone with 20 years experience working on both sides (corporate / open source) for companies doing both (1) and (2) above.