http://tor.iykpqm7jiradoeezzkhj7c4b33g4hbgfwelht2evxxeicbpjy44c7ead.onion/about
The network needed to be operated by entities with diverse interests and trust assumptions, and the software needed to be free and open to maximize transparency and decentralization.
That's why in October 2002 when the Tor network was initially deployed, its code was released under a free and open software license.