Tesla's solution might not be the cheapest one.
As an engineer (without long experience) I'm able to sketch cheap solution in my mind.
Very shortly: additional coupling underneath the vehicle (like most inductive solution).
Coupling has IP67 rated shutters that retract as soon as plug (installed on garage flood for example)
and socket push together using actuators (up to 3 axis). Mating process is coordinated with few
cheap magnets. Nothing wrong with safety as EVSE's always have RCCB protecting people.
So imagine something similar like wireless charger below Nissan Leaf
Just that it has few actuators that move appropriately designed plug (J1772 needs some mods at least) into place.
Possible that 3-axis motorized plug is cheaper to make than massive coils in wireless solution.
If motorized part is installed on the floor (not in the vehicle) it must have small energy reserve for blackout removal.
(also possible to make spring loaded retractor (as soon as vehicle releases plug will come off with a bang).
If motorized part is installed in the vehicle then stationary part will be very cheap to make.
Tesla will NOT fail with the whole autonomous vehicle fleet just because they are unable to charge vehicles autonomously