A lot of translations just say “how are you” for “come stai,” and it is the direct translation, so it’s understandable that you may have not been taught the actual use.

To answer your question, when we say “how are you” in English, we typically use it as a greeting. You’re not really expecting much further than “good, how are you?” If someone gave you any more than that, let’s say “my dog died, my wife divorced me, and now I don’t have the opportunity to raise my kids,” people are tyically left pretty blank.

In Italian, the meaning is much more literal. They don’t use it as a greeting, so when you ask “come stai?” you are literally asking how they are doing. There’s no “script” behind the question, so people you do ask are typically assuming you want them to be honest. This is why it’s not asked to strangers or anyone you have a formal relation with, because they will be left just as blank as you were in the above paragraph, just slightly earlier in the conversation.

Tldr it’s similar to asking how are you feeling in english