Well, IME the subtle ratios of tahini, lemon, chickpea, olive oil, and garlic can have a massive difference on the taste of the hummus ... and, of course, the actual ingredients (freshness, etc.) matter too! Even something as basic as tahini comes in a multitude of types.
And that's before you get to adding the salt, pepper, and possible spices (some people like sumac or other variants). A "Middle Eastern" restaurant will serve a subtly different hummus depending on where they from in the Middle East- an Israeli, tahini-forward hummus will taste quite different than a Jordanian hummus that uses yogurt.
Like many seemingly simple foods, the devil is in the details.