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Except for the fact that open source software does not have to be given away for free. With appropriate licensing, it should be possible to ensure that every owner of a piece of commercial software is given personal access to its source code, without being allowed to redistribute copies nor derivatives of it.
In fact, I have been trying for some time to get OSI approval on an OSS license that handles this use case. However, at this point, it still needs further lawyer review. People on the license-review mailing list have given me some pointers to this end, though, so hopefully I should be able to do that. Edited 2013-04-15 15:52 UTC