You’re welcome to limit your definition of hacking, I prefer to keep an open mind.

Since you used an elevator as a metaphor, to me, it’s like opening an unlocked elevator control panel to reroute the signals to achieve a goal that’s not possible via a locked panel; for example, access a floor that normally would require a high security key. Easy, yes, an intended use of the system, no. Would doing so potently be trespassing? Depends on the context, but possibly, if not likely, yes.

That's an interesting example since some of the most popular DEFCON talks on youtube are about elevator hacking, which includes pressing buttons that are right there on the panel