GPS works fine.
GPS works fine.
Until it is hacked, or jammed, or the EU shuts you off...
Until an enemy attacks the satellites, jams the signal, or spoofs the signal and sends you off course.
It also does not work underwater or underground, and it requires a receiving antenna, which is vulnerable on an armored vehicle.
Deep space probes can can not use GPS. There are lots of military reasons why GPS is not a universal solution.