Headlights set off motion detector

If headlights are causing my doorbell to ring, and lights are considered ‘Motion’, why doesn’t my doorbell ring when the Amazon delivered guy leaves a package on my doorstep? They never ring my doorbell, they just leave the packages. And I’ll get a ‘Motion’ or notice that I have a package, but never does my doorbell ring when someone is just standing there. They have to push the button. Therefore, lights shouldn’t trigger my doorbell to go off? This just doesn’t make sense. It’s annoying to have your doorbell ring in the middle of the night.