But if you're using the Uber app on your phone, and no "transactions" are being processed through the car, then you're allowed to use those services with a human driver, because Tesla has no way of knowing what the human driver's intentions are.
However, yes, in autonomous mode, someone somewhere has to be able to digitally summon the car.
And while I understand people saying Tesla is doing it to protect a revenue stream, there's also a FANTASTIC reason they're keeping it locked down to their own app:
Security.
To be able to summon an autonomous car via an application, that application has to have access to certain portions of the car's software, as well as the network the car is passing it's data over.
If someone were to use Uber or Lyft as an internet backdoor to hack all autonomous-enabled Teslas.....that would be very very bad.
I applaud Tesla for "keeping people out", and I hope they highlight the security implications when they introduce the "Tesla Network" next year.