That's not quite true. Asian countries have used mobile phone data in some cases but so have western countries.

South Korea got somewhat lucky (so far) due to the weird way it got into the country, via a cult that was already in effect socially distancing themselves and that was filled with young people. But now their cases seem to be growing again.

Also what do you think happens to mobile phone tracking the moment someone walks into a subway system? Orwellian surveillance isn't a magical panacea.

Because of states rights as well as legal rights afforded to every US citizen, a lot of the same options / technologies aren't available by design. You also have to deal with two distinctly different cultures with drastically different outcomes of citizens actions.

We can look to them for inspiration, but to expect the same actions / outcomes isn't prudent and pulls away from the focus of figuring out what we can do here in a realistic manner.