Why hasnt a turntable manufacturer produced a table with automatic tonearm return/shutoff?

I prefer convenience of automatic as well. But the extra weight of the extra mechanical parts mess with the delicate sound balance, or so I've been informed. 

Early this year I restored an old automatic Dual turntable from the 1970's era.  All I can say is a lot of German engineering, parts, and production cost all went into this feature.  It detracts from reliability and the quality of more important parts like the tonearm and drive system at a given price point.

   Pro-Ject has 2 automatic turntable options. One is $499 and the more expensive option is just over $1000. Decent quality and most of them come with usable, if not spectacular MM cartridges.

I would think that a device to raise the arm at the end of play would be quite easy. Simply When the arm reaches the inner groove, it triggers a sensor that raise the arm. However, a device that moves the arm back to it staring position would be much more problematic, as it would require physical interaction with a delicate arm structure.