That's beside the point. Let us suppose for a moment that Apple had built OS X atop a Linux kernel. The fact is that their secret sauce would remain at their whim to license as they please; Cocoa, Finder, and so forth run in userland. They wouldn't be covered by the GPL anyway. That being said, if someone were to take FreeBSD and make changes exclusively to the kernel, and did not wish to release it, they wouldn't have to. It's their prerogative.But they will never contribute back ALL of their modifications, and in effect, this means that in pretty much all cases, the proprietary derivative is entirely incompatible with the upstream. Can you run MacOS software on FreeBSD? Or PS4 games? No you can't. That's the problem right there: these corporations can take the free base of BSD, add their secret sauce, and use the resulting product to gain an advantage. The parts that don't matter that much to them, the parts that aren't part of the "secret sauce" get contributed back for free maintainership.
Once again, this does not apply to those who seperately build on top of the product. For example, Google, seen by some as a champion of open-source-software (I can't see why, personally), have the ability to close Android's source north of the kernel if they so desire-- thus keeping their secret sauce private. And yet they do not.Compare and contrast with the Linux kernel: there's dozens of corporations, all working together, all releasing their modifications openly, because they can trust that the code also stays open - meaning that none of their competitors can do what the BSD-using corporations do: take their contribution, run with it, add secret sauce and profit. The fact that the code stays open for everyone is like a safety, a guarantee, that everyone - even competing companies - can safely contribute code, without having to fear that they'd be shooting themselves in the foot.
Some do, some don't. I'm not a professional programmer, but I can't help but feel that trying to abide by all these licences is a pain. I can't say how many companies feel this way, but (particularly with the emergence of the GPL v3) it has become clear that they do exist. Just imagine-- you're designing a product which uses some GPLv3 software in an embedded context. Per the terms of the GPLv3 you have to make the compilation of your own copy of that software feasible, and then make it possible to load it into the embedded device in replacement of what they distribute. This is a pain, particularly if, for example, the embedded device also relies on proprietary software which the company may not redistribute except within said device.No it's not, it's an imaginary problem. Plenty of companies are able to make succesful business with Linux, and the existence of multiple different licenses isn't stopping them.
This is a valid point. However, I still feel that the convenience factor is an element, and it would appear that it is.No, the reason of that is because of the rudimentary copyright law (and poor enforcement of it) in China, which pretty much means that the Chinese can take whatever license they come accross and wipe their arses with it.