[charcircuit]

>Make available the original source code when you distribute any binaries based on the licensed work

You only have to make it available to people you distribute the binaries to. If people with the binaries don't want it or if they want to keep it to themselves they are free to do so.

The reasons why corpos contribute back to upstream projects have nothing to do with the license. Usually it is just to shift the maintenance costs to the upstream developers.