And in the README.md they have attribution, mentioning the licenses of the underlying dependencies.
tl;dr: The LICENSE file is for this project, not the underlying libraries they copy-pasted in (which other than say the png files, seem to have their MIT/BSD info in them).
That's a good reason to include license terms in each file. I don't think that Wordpress people were malicious here. The LICENSE file usually contains the global licensing terms (as seen in many GNU projects). Each source file should still contain the license or a mention of the license. MIT-like licenses are usually put verbatim in each files, while verbose licenses like GPL just get a pointer to the LICENSE file.
On some files, the MIT license is correctly present at the top of the file:
Well, you can relicense the MIT-licensed code. They might have had to include the text of the MIT-licensed component license, but that would still have no effect on the license of the derivative work - it would be GPL.
That license change would only apply to the changes and additions, any of the original code would still be MIT licensed, also if the changes are trivial then the whole re-license might fall through.
Copyright would still lie with the original authors as well, after all sub-licensing allows you to pass on the rights that you already have, but does not give you any new rights.
Since the MIT license is mostly a super-set of the GPL you will lose some of the MIT parts if you sublicense but if you wish to gain more rights than what the MIT license already provides you with it will likely not work when tested in court. The best way to deal with stuff like this is to stick to the original license unless you have consulted with an IP lawyer that signed off on your plan, it is very easy to get these things subtly wrong.
There were over 1000+ commits made in over a year -- all of those changes and improvements are GPL. (You can make GPL mods to MIT code and release those all as GPL.) If Wix had used the original ZSSRichTextEditor they would have been fine, but they didn't.
The key thing to understand is that being “compatible” with the GPL means that you can take code written under an MIT license , and put a GPL license on it if you want to. The MIT license allows for this, but, the reverse is not true. The GPL does not allow you to take GPL code and change the license to MIT, and it definitely doesn't allow you to take open GPL code, and make it proprietary.
You can include MIT & BSD libraries in a GPL-licensed app but you can't include the resulting GPL work back into an e.g. BSD-licensed app. Same as you can include jQuery in a proprietary app which has its own license.
They may be compatible but you cannot remove someone else's copyright and license from their source code. They specifically say you must include the license.
Wix may still be in the wrong, but WordPress is definitely in the wrong for removing copyright and license. IANAL but both of these companies would look awful funny in court because disregard for other people's licenses doesn't help your case when someone disregards your license.
As far as I can see the files that were originally under MIT still have their original copyright statements intact, as comments above illustrate. Which files are you alleging have had their credits removed from?
In this case the WordPress-Editor-iOS retained the copyright notice in the file copies from the ZSSRichTextEditor project. But did not include the LICENSE file.
Also the wordpress-mobile developers mixed their source code with the MIT licensed one. Just one LICENSE file I can find in the WordPress-Editor-iOS.
The MIT/BSD projects are not separated out. I think they can claim GPL license on their created code, but that has to been clearly identified. Easier if they removed the MIT/BSD components, and make them git submodules.
In addition, the wordpress-mobile developers created code do not contain a copyright notice.
> The MIT/BSD projects are not separated out. I think they can claim GPL license on their created code, but that has to been clearly identified. Easier if they removed the MIT/BSD components, and make them git submodules.
Using MIT licensed projects doesn't require you to keep the code for the parts you've adopted eternally isolated from your own. If that were a requirement, that would entail an inability to make any improvements without also distributing those improvements under the MIT license―which is directly antithetical to the permissiveness that the MIT license aims for. The parts do not have to be easily separable.[1]
To be clear: mixing MIT source into a project (whether by copying files, or by copying snippets) and distributing the result under a license that is not MIT is something that is absolutely kosher. The only requirements are that you have to reproduce the MIT license text and any corresponding copyright notice somewhere when you start distributing the thing to other people. Look into what Google and Apple do with Android and iOS or type about:license into Firefox for three really great examples of how to satisfy the requirements of third-party projects when incorporating others' code into a project with a license that differs from the original.
The only thing Automattic is in the wrong with here is to have linked to the licenses and copyright notices of the original project rather than include a copy of if inside their own distribution, which is arguably a faux pas in some circumstances and in some circles, but it's easy enough to remedy and no court would ever award past damages for it.
1. For a license that does work like that, i.e., a weak, file-based copyleft, you can look at the MPL. http://mozilla.org/MPL/
[edit: I guess with your edit that is exactly what you are saying, so how can it be legal to pull that stunt?]