I started to watch Muay Thai recently, and something I can't really wrap my head around is exactly what throws are illegal. Muay Thai abstains from many throws and takedowns you'd find in grappling sports, but it still has leg sweeps and throws from the clinch. I know that Muay Thai does not allow groundfighting, but I never even see a shoulder or hip throw. Rules aside, those seem like good options in a clinch and can put an opponent on the ground as you remain standing, just like leg sweeps.
So what's the rule-of-thumb for a legal throw in Muay Thai and what's the motivation for it? I have considered if throws were just historically unused, but apparently the martial arts (Muay Boran) that formed the basis of Muay Thai had grappling and groundfighting. I have also wondered if it has to do with a history of safety regulations, but I only found information about fighting equipment, weight classes, banning groin strikes, the usual stuff.