Why is prostration to idols and planets considered apostasy in all cases, regardless of whether it is for greeting or worship, while scholars differ concerning one who prostrates to a human with authority with the intention of greeting, not worship?

Prostrating to humans with the intention of greeting, not worship, is forbidden and considered a major sin by the majority of scholars, but it is not major disbelief. This is in contrast to prostrating to an idol, which is disbelief that expels one from the faith. The jurists have a consensus that prostrating to an idol is disbelief that expels one from the faith if the prostrator is sane, adult, and acting of their own free will. As for prostrating to something other than an idol, such as kings, it is forbidden and a major sin. If the intention is worship, it is disbelief. If the intention is greeting, scholars have differed on it. The difference between prostrating to an idol and prostrating in greeting to a parent lies in the jurists' reasoning that prostrating to an idol only originates from mockery of religion or denial of it, unlike prostration for greeting.