Wow! mistyping a number stops the GPS, auto pilot and auto throttle from working. I'm incredibly surprised that what would seem to be a relatively simple UX / v

Wow! mistyping a number stops the GPS, auto pilot and auto throttle from working. I'm incredibly surprised that what would seem to be a relatively simple UX / validation issue could cause such a huge safety issue; flying in the wrong direction towards inbound aircraft and the plane mistaking its location by 11,000km. Very surprised; maybe someone with experience writing flight control / management software could explain?