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