Elon said himself the hard part was mass manufacturing the damn things, and they're clearly failing to do so properly.
It's an interesting situation certainly. You hear a lot of people comparing Teslas to Audis and BMWs to point out how poor their paint is, awful panel gaps, and how lacking their interiors are, but I've never heard anyone compare powertrain reliability or quality.
The value of a Tesla comes form the advanced telematics and EV powertrain, the later of which is more expensive to produce than what's found in an Audi or BMW.
In terms of how well the interiors hold up over time, I don't think that any of them hold up any better or worse. My 2+ year old Model 3 looks just as nice inside as the day I got it, I'd say the same of my friend's BMW 5 Series that was about 2 years old when she sold it.
In terms of maintenance costs, a Tesla requires maintenance ever 2 years at around $150 a visit. BMWs typically get free service for the first 3 years, but after that you're looking at something like $250 every 5000. So if you're expecting to keep your car for more than 3 years there's certainly value in that respect. The high reliability and low maintenance costs of Teslas also increase their resale value compared to other vehicles.
Personally, I find the interiors or Audis and BMWs to be a lot of pomp and circumstance to help their owners justify the price. There's a lot of lights, noise, and different material finishes to make them look impressive but is that better? I don't think so.
They definitely have strong points too, the software package is nice and their charging network is good, but that's where my compliments end.
Yes the paint and interior aren't as good as a comparably priced BMW or Audi, they had to cut corners somewhere to hit their price point. I'm glad they chose a simplified interior and crappy paint over compromising the power train or telematics.
It's like complaining that a 26.73gram gold nugget isn't as shiny as a brand new silver dollar.
I just don't see any justification in worse quality than a 1995-ish SAAB because It's got a touch screen.
The engine and transmission are simpler but not without their challenges, in addition you have to consider the battery which is also part of the powertrain and is the major cost center.
The gearboxes in EVs have to withstand much more torque than a traditional ICE vehicle which is why most manufacturers have stuck with direct driver or reduction gear boxes instead of a traditional transmission. They're simpler to design but require more expensive and stronger materials.
A 3 phase motor can be simple and cheap if it's the induction motor used in something like a forklift but EVs need more power and efficiency and have a much greater duty cycle. The Tesla Model 3 uses a switched reluctance partial permanent magnet motor and an induction motor in the dual motor, the Nissan Leaf uses a synchronous electric motor, the BMW i3 uses a synchronous permanent magnet motor, the VW ID.3 uses a permanent magnet brushless motor.