You can release code and still violate the GPL in other ways. For example, there are binary blobs out there and the GPL is pretty unequivocal on this point: "The source code for a work means the preferred form of the work for making modifications to it."
It depends whether the binary blob is a derived work or not.
Re:Google’s not-so-secret new OS
by matthewmacleod on Wednesday February 15, 2017 @03:38AM
(#13650586)
Releasing binary blobs is definitionally not releasing the source, though.
No it's not the status quo. The major OEM's do release their code. Yes, there are some Chinese OEM violators, but that's typical of China.