As the recent years showed, most companies have no problems "sharing back" modifications of open source products. Some companies (MS, Apple) even open sourced t

As the recent years showed, most companies have no problems "sharing back" modifications of open source products. Some companies (MS, Apple) even open sourced their own developments. The problem is not sharing back. The problem is, that GPL forces the whole program to be open in source and freely shareable between people. Most commercial software cannot exist with such a business model.