Everywhere I've ever worked has been perfectly fine with my open source contributions, and never asked for a copyright assignment (to be fair, nor have they offered one: this is the kind of thing DannyBee finds untidy and unsafe). This madness is an affliction of large companies, and in particular their legal departments. And, given the small sample size I have of "large tech companies", Google isn't much better than the norm here.

Basically, demanding copyright assignment in exchange for "simple appropval process" seems like a poor bargain to me. It's not at all unreasonable to expect that employees be allowed to keep their own IP, and to argue otherwise is IMHO dangerous to open source.