In the 1950s, Fairchild made a turntable which used a variable frequency oscillator to control speed, and there were a number of turntables which used gears to couple the motor to the platter. I don't know if they were equipped with that cool red "gear shift" knob though!They're not a priori.
The (sort of) aforementioned Fairchild 750 is belt drive -- and engineered & built to a level of precision that was probably never duplicated in any other piece of transcription equipment.
View attachment 108774
The good idler drivers are -- good -- in terms of speed stability, but it takes great pains to get them quiet.
PS Don't discount the Garrard 401 either. Not as old-world charming as the 301, but quite fine.