US GPS has better accuracy, but more importantly how many Tornado rockets are produced every month? If it was in large volume the war would be over.
HIMARS actually works, apparently the Tornado S and other Russian systems don't have anywhere near the same accuracy or effectiveness.
There is a reason the Russians rely on western components and even some ammunition smuggled in to their country.
Do you have any idea on how it works and what wins wars? All these systems are equally accurate, it is not some sort of space alien technology. They are obviously produced in higher numbers than GMLRS.
Also the GPS guided missiles have very limited applications. Only the Nazis believe in wonder wespons which win wars.