Orange,
the main advance is having rapid tests that CDC/FDA was not approving for a long time because they are not as good as PCR. The role of the tests is statistical – it shows with high probability that someone is infectious right then, rather then telling 3 days later that someone has a minute amount of virus with 100% probability.
It probably matters a lot for people who are in risky environment but not so much that nobody cares and everyone is getting sick … then, removing those who are sick will stop transmission even if it does not guarantee safety of one individual. There are lots of “interesting” techniques – batch testing, where spit of multiple people is tested in one shot; wastewater monitoring that quickly picks up the virus in population even if they don’t bother to go to doctors. I am not sure all of this is used correctly and timely, but it is getting better. Many colleges test a lot and post numbers publicly. One college near me has 100 times more cases this week comparing with October.