Flarm in the US

You may be pleased to learn there are many good soaring areas in the
country where the glider density is so low, colliding with another
glider is the least of your worries. In fact, that is a - maybe "the" -
major reason that Flarm is not popular in the USA.

A national contest is not one of them. There, colliding with another
glider is undoubtedly one of your major worries. I think this
realization is moving the contest community towards Flarm. It may
make sense for contest gliders, and those operating in high glider
traffic areas (Whites, Ridges) to get Flarm, recreational gliders
operating in low glider but high power traffic airspace to get
transponders and Pcas, and lucky guys out in the middle of nowhere to
simply open eyeballs.

John Cochrane