The US of A has no problem with gliders colliding with power of any kind because there ARE VERY FEW GLIDERS FLYING IN THE United States!
My limited experience in sailplanes in the US includes flights during which I was looking down at approaching airliners from 17,990 ft (in Class E). That happens all the time at the closest glider field to me. They're still using Schweizers as trainers BTW, but the flights I mention were in a Duo Discus owned by a friend.
Its helpful that US VFR Terminal Area charts show typical airliner tracks and altitudes through Class E, approaching terminal area Class B and departing upward into Class A above 18,000 ft. There's a lot of light aircraft in that Class E airspace, most of them talking to nobody on the radio. Good radar coverage and good approach controllers also help, along with Mode C being almost universal around US terminal areas. Those that don't have Mode C need to be careful, but armed with the right information and attitude among all parties there are very few issues. It's really a matter of organization and standardization as much as technology - which makes one wonder why ADS-B is being implemented... That's another story but I think one (very) long term goal is to replace ATC radar and eliminate transponders. That then provides a route for non-electrical aircraft, given the much lower electrical power demand for ADS-B Out.