Pilots of aircraft also depend on getting the altimeter setting, which is a correction factor to allow their barometric instruments to show them an accurate altitude or clearance to terrain. Each air traffic controller will routinely give the altimeter setting for that area so the pilots know what to set on their altimeters.

There are various methods for GPS devices with a barometric sensor use to calibrate their reading to the actual elevation, but that initially takes effort from the user and only works for predetermined locations. And the GPS device AFAIK only calibrates itself at the beginning of a ride. So normal changes in barometric pressure will produce errors in what is actually done.

Almost any ride I do, the elevation I left my house at is not the shown elevation when I return.