The only reason I can think of is that Elon Musk - in the beginning - was open to sharing EV technology to help with a sustainable future. Any other car company would probably not be interested in sharing.

Now - is self-driving in the same realm?

There might be two angles - supporting electric vehicle development and maybe safety/lives saved.

for electric vehicles it might apply - but I don't imagine tesla would share technology that could be used on fossil fuel vehicles.

for lives/safety - who knows, but it would be good PR ...if tesla still does that without a PR department :)