Because it would be a retro-fit, and, well, because Tesla can get away with charging an arm and a leg. As an option for a new build, it might be cheaper, or bundled into some other options.
Beg to differ here. Tesla can't afford to alienate the customer base in their most important market.
BTW in EU cars, the tech package is required for the parking sensors option.
The price for driving Model S early is seeing it improve in later iterations. This will always happen for every car of any make and model.I am so upset about the parking sensors now that I see how nicely done they have integrated them! Dam!