The Android OS may be open, but the customisations that the different phone makers use probably (almost certainly) aren't. There are several reasons for this:
- The Android license does not require changes to be made available under the original terms.
- Most of these manufacturers are still newbies on the open source concept, and are likely "scared" by potential legal trouble of sharing out.
- The custom UI is a "differentiating factor" and thus not something they'd like to give away for their competitors to use.
The last one is obviously the most important reason.
Oh, and
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