Electric is a much smaller market. And nothing about self-driving requires an electric vehicle.

I'd consider buying self-driving features on a regular car. Electric would be a total deal-breaker for me with today's technology.

Edit: upon further reflection I think it's likely that Apple is just developing the self driving tech and is unlikely to be actually planning to build cars, electric or otherwise.

That last paragraph. The Android model would be very attractive for cars, even for Apple. On smartphones, that model suffers from the hardware being all too indistinguishable. Glass rectangles with or without rounded corners, maybe a button here and there. Car manufacturers by contrast have a century of experience with making mechanical differences count, on top of the same UI everywhere.

For Apple and Google, the case is clear: if they want to defend their incredibly valuable gatekeeper position for local search (the market formerly known as the yellow pages) they need to provide the UI for the car or else they lose much of that gatekeeping. The question is, will any car manufacturers be willing to play, or are they all trying to succeed where Nokia failed?

I don't know much about engines nor cars but I am guessing that even with electric motors one needs gears? If so then there would be a need for gearbox oil.

There isn't a transmission/gearbox, but Teslas undoubtedly have differentials in some form which is where you would definitely find oil. I change the axle oil about once a millennium in my Jeep, so Tesla owners probably don't even think about it. To your point, though, there is probably a single reduction gear to lower the rotation speed of the motor and it might need oil. (Reverse does not require reconfiguring anything in an electric system, given that one just flips polarity. Electric motors have different torque characteristics which obviate the need for traditional gearing.)

I'm guessing service on Teslas is the usual: brake pads every century given that regenerative braking does most of the work, greasing bearings every now and then, coolant, tires, wipers. Internal combustion is extremely complicated in comparison.

No you don't need a gearbox.