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

@lewm no, it's an obscenity. 

The older Kenwood KP series tables have auto lift only, I like that feature and the turntable sounds great. I believe there was also the KD series which might have auto lift as well. Does not seem unreasonable to have this feature

I once looked at the underside of my Dual 1019 and saw a lot of hardware -- gears, cams, levers, hooks, whathaveyou to change records on the spindle, return the arm to the armrest, and shut off the motor.  I would rather have as little of this hardware as possible.  I never used the changer, and I don't really need the arm return feature.

My wish list for turntable/arm automation:

1)  Arm interchangeability, so I can pick a third party arm.  For example, I had to give up the dedicated JMW arm on my VPI TNT HRX to install a Graham Phantom.

2)  Auto lift the arm at the end of the record.  Lots of solutions for this including the Little Fwend, Audio Technica Safety Raiser, and my favorite the Expressimo The Lift (mine is slightly modified).  Etc.

3)  Auto motor shut off at the end of the record.  Maybe cut the power using an electric eye sensor when the arm gets to the runout grooves -- or?

This would let me fall asleep and/or walk away during record play.  I would be happy to come back in the morning to return the arm to its rest and put away the record without concern about the motor spinning all night with the stylus on the vinyl.  Hopefully, this can be done with any arm without encumbering the arm with any attachments or modifications, preserving interchangablilty and the purity of the original arm design in mass and resonances.  Also the reduced complexity suggests better durability and easier repair.

Again, from a manufacturer’s point of view, the higher end “audiophile” products and even the mid-portfolio tables in the company’s lineup will most often lack this feature.   It’s not a question of “can/can’t”, it’s a question of “should/shouldn’t”, and given the total lack of demand for this (at the U.S. turntable manufacturer I worked at) especially at the mid-upper portion of the product portfolio, it makes very little sense (financial sense, engineering sense, marketing sense) to do.   For buyers at the upper ~80% of the product line, there was general consensus and agreement that other engineering focus areas — managing resonance and vibration, tonearm design and manufacturing, plinth design and engineering, noise elimination, proper grounding especially of tonearm wires, how to handle VTA, how to handle anti-skate, motor speed consistency and noise, etc., etc. — are collectively much more important than a limited-interest convenience feature like auto-lift/auto-shutoff.   
The only folks I remember asking about it were those looking at the more affordable tables in the lineup    

I was a bit surprised that in my few years there, speaking to customers every day, it ever-so-rarely came up at all in discussion.  
 

Make what you will of these observations, just trying to give some perspective from the turntable company’s POV.    YMMV.   

Maybe there should be another new thread on the subject of falling asleep whilst listening to vinyl.  More than one of us has confessed to it. For me it is unthinkable, maybe in part because I am loathe to run my tube preamplifiers and amplifiers overnight, lest a blown output tube would take out a speaker. (Two systems, both with OTL amplifiers driving ESL-type speakers. In the case of the Beveridge 2SWs, the output stage has 3200V across it to direct drive the speakers, and I don't think there is anyone alive who can competently rebuild a Beveridge ESL panel, even though I have a roll of aluminum coated mylar sufficient to do the job.). But also,  I am riveted to the music, and when I sense that I am tiring of it or that it is time for bed, I pack it in.