Someone not totally familiar with the button positions might be trying to press the gas cap button, the ECO button, or the hazard flasher, or might just be pressing around in general looking for a button.
Three seconds seems perfect to me from a safety standpoint. Makes sense to me.
Besides, there are transmission controls which operate instantly. Moving the selector to Neutral should disengage the engine from the driving wheels, as would depressing the clutch pedal.
YMMV