Yes US have had a high loss rate in their early UAV ops. However, this is because such ops presented major technological challenges and were often done in deployed, combat conditions. US Gnat, Predator, and Global Hawk ops over the last 10 years in Croatia, Bosnia, Albania, Kosovo, Serbia, Afghanistan and Iraq have proved the reliability and utility of such assets.
God forbid they might be used in "deployed, combat conditions"! That sounds as if it's not fair on the poor wee robots, as if their real role was exercise. Deployed, combat conditions are the test of quality. I'm fairly cynical about the supposed prospect of an air force made up solely of E3s, uavs and biz jets with fancy electronics supported by privatised tankers.