This is because Apple doesn't seem to relate to how real people do real things. For example, how they use a calendar.
When you book a flight, the airline gives you an itinerary with times on it.
Those times are LOCAL TIMES. Is there anyone on the planet who thinks that United is putting non-local times on its itineraries, as if you're not going to change your watch or something? YES: Someone at Apple thinks that.
Consider the craven stupidity of this "logic:"
So neither of these settings ensures that your iPhone will go off at the specified numeric time shown on the phone's screen. In fact, it doesn't appear to do anything. It's incredible: Apple's handheld Unix computer can't do what a $9 alarm clock can.
And yet Apple gets a free pass on grossly defective designs like this, which aren't just cosmetic annoyances. They cause people to miss important events. Why do you allow it?