How low are these satellites? I wouldn't expect the altitude of a plane to be any significant proportion of the altitude of a satellite.

The satellites are probably greater than 400 km altitude, or so, while the plane is probably 10 km. The plane is in the same rough order of magnitude as really tall mountains, which the satellite is presumably designed to compensate for, so I agree with your general assessment.

The Google Maps image copyright is for Maxar, which means the collector is likely Worldview-3, which is at nominally 614 km above the Earth.

https://earth.esa.int/eogateway/missions/worldview-3

The shadow is 750 m away and the sun is about 15 degrees off noon, so the B2 altitude is roughly 3 km. Cousin comment says the satellite altitude is 614 km, so I wouldn't expect parallax effects to be dominant. This is also evidenced by the fact that both the plane and ground are in focus and the plane is measured to be 70 feet long in google maps, which is what it is specified to be in reality.

That bomber is also likely quite low, since it's based out of an air force base in that area.

Sure, but when the word "calibrate" comes up, you want to account for even the not-very-significant factors.