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

JVC made a high-end DD table that solved all the issues people worry about regarding SQ and automation - the QL-A7. It was equal to or better than the offerings from Technics and Denon (except it lacked the very cool Denon plinths). JVC designed the table so there was no mechanism to interfere with the tonearm's performance while playing the record, and nothing to service. The JVC tonearms were also longer than most, with lower tracking error to better support cartridges using the then new Shibata stylus shape, required to decode CD-4 Quad recordings, and which was then as now, very sensitive to tracking error. You may want to consider finding a good used or rebuilt QL-A7.

If you can spring $300,000 or so for a Wilson Benesch Table One, you will get lots of remote-control features including start and stop.  You will be able to adjust the VTA from your armchair, and remotely adjust the rotational speed in 100ths of an rpm.

To achieve this, it comes with a dedicated network.

Through the GMT® Control APP, users can finely tune various parameters to tailor their listening experience to their preferences. This includes adjusting the speed of the OMEGA Drive to accommodate different record formats, with the ability to fine-tune the speed in incredibly precise increments of 0.01 RPM. Users can also easily start and stop the OMEGA Drive, as well as lift and lower the GRAVITON® Ti Armwand with precision.

Furthermore, the GMT® Control APP enables users to adjust the PIZEO VTA System with remarkable precision, allowing for micro-level adjustments in 1 nanometer steps. This level of control over critical aspects of a turntable system is unprecedented and it legislates that users can achieve optimal performance and playback quality with unparalleled accuracy.

No wonder some authorities think it is a bargain!

I worked at a well-known U.S. turntable manufacturer for a few years.   (A) there was shockingly little demand/ask for it, (2) and for those that wanted it, we’d add an AudioTechnica 6006 or Tru-Lift or similar add-on unit.   We even carried them at the factory.    I can count (maybe on one hand) the number of them I sold with new tables in a few years’ time.   And, that’s just the “lift” — no auto-shutoff.   So, from an engineering perspective, near-zero demand = a feature that’s not worth the effort (as far as being integral to the table).  It’s really just that simple.   It’s always been a staple of the Japanese tables (and some others) but never truly caught on with U.S. audiophiles.    I literally had the privilege of speaking at length with thousands of audiophiles about their analog systems, and it was ever-so-rare that anyone would ever bring it up.   
 

Jim 

The old record players played a stack of records automatically. I had a 45 rpm record player in my hot rod that played a stack too , only skipped on big bumps. Later on I got a Thorens player with a Rabco arm which was some improvement. The first time I heard a c.d. I sold the record player and never looked back. Nowadays I have a high end SACD one bit player. In my opinion no record can hold a candle to it. I don't get the record thing but whatever floats your boat.

It was always my understanding that any type of additional mechanation or masses added to the tone arm would/could bring additional methods for coupling noise and possibly affecting proper tracking.