It's interesting that we're so used to the GUI buttons having that specific behavior of only triggering when releasing, even if you exit and enter the button area while holding the mouse button down, etc.
IRL 99%+ of buttons work by just doing the thing as soon as you press them. But a button that works like that in a GUI would feel wrong.
IRL 99%+ of buttons work by just doing the thing as soon as you press them. But a button that works like that in a GUI would feel wrong.