I recently did a test-drive and the guy maneuvered the car out of the dealer lot by driving backwards and looking out the rear window, completely ignoring the fantastic surround camera and sensor view that popped up on the huge display in the car... Great job selling that feature, buddy.
Another reason is that Teslas are "cool", and get a lot of press in non-automotive circles, which means that a lot of people think they were first with a lot of technology, which simply isn't true.
And a possible third reason is that quite a lot of tech people have been researching and toying with the idea of getting a Tesla, but those same people have never researched similar vehicles from other manufacturers, so they have no idea how they compare.
I had a 2014 Mercedes E-class, its self-driving capabilities was on-par with a 2014 Tesla. However, Tesla offers over-the-air updates of their vehicles, so existing Teslas got better, while my vehicle stayed the same, so that's a point they should have credit for and something they actually do better than most other manufacturers.