Yes, platter speed can vary in accuracy from one brand to another. Some brands give adjustable speed control. Better turntables have no real issue with speed problems. Very few are absolutely perfect, but speed regulation under one tenth of one percent is not unusual for a good table. I don't know of any tables that have speed variations of one percent or more. Rega tables commonly run about a half percent fast, and this is pretty well known, and most people don't really notice it.
By the way, I make custom guitars, and a "perfectly tuned" guitar is rarely that. Intonation is nearly always off somewhere on the scale. Nobody in this world achieves total perfection on anything. If there is any variation in string thickness, action height, fret wear, neck set, nut wear, bridge wear, etc., there will be a problem somewhere, and this describes just about every guitar there is. Perfect open-tuning is just the beginning. Controlling a motor speed is much easier, believe me.
By the way, I make custom guitars, and a "perfectly tuned" guitar is rarely that. Intonation is nearly always off somewhere on the scale. Nobody in this world achieves total perfection on anything. If there is any variation in string thickness, action height, fret wear, neck set, nut wear, bridge wear, etc., there will be a problem somewhere, and this describes just about every guitar there is. Perfect open-tuning is just the beginning. Controlling a motor speed is much easier, believe me.