help needed with sat image question please

I have just observed something that I am not sure that makes any sense but,,,,,
I have GOOGLE EARTH ok and I noticed that while looking at DENVER AIRPORT or others that looking from the satellites camera down at the planes, as i zoom in and in and in, it has to get to an altitude of like 12,000 ft or less for me to recognize the planes on the ground at the same approximation in size as when I stand outside and look up at them as they fly overhead. Even the ones leaving CT's are closer to 11,000 ft in altitude than the so called above 28,000 required by professionals like Nasa explain. If i am to zoom out to 25,000 ft or more I cant even make out the outline of a jet on the ground.
I know most will think this silly, but that's ok cause it is just something to think about on a Saturday Maybe it is not the same as looking with the naked eye as looking through a satellite's camera.

can anyone shed some light on this please ???

thanks