Sure, many things have been contentious... changes in general meet with resistance. That's not a uniquely Red Hat, or even Canonical, thing. But in the end, and this is just my impression as I'm no longer a major user of either company's distro, Red Hat seems more interested in working with (with the notable exception of one specific prolific individual) other developers and distros while Canonical doesn't. It shows in the results: most of Canonical's major initiatives don't even survive in their own distro for too long either because of user revolt or the other distros go in a different direction. (they lost me as a user because of a couple of them)

(If there are distro maintainers / package developers who disagree, I'd be interested to hear about it. Again, this is just my impression)