Morkus from Orkus
Wow, you all want to make a lot of that one word, "usually," in a Sage Advice response, while hand waving away that everything in that reply that clarifies and assumes that surprise is decided with Stealth. The general rule for deciding stealth presumes hiding, it says so right there, and nowhere is there any class or racial ability indicating a more specific rules overriding that.
That's because the word "usually" is an extremely important word. If they meant always, they would have said so. That the specifically chose usually means that their intent is that what follows is not 100% and there are other ways to go about it. All the clarifications are to the "usually" portion and not the portions that are outside of it.