Part of what you say makes sense and is true, but the general public doesn't understand glide ratio's and that losing and engine doesn't necessarily result in a crash.
I have talked with UAV manufacturers that indicated there really isn't any sort of control over where a UAV lands after an engine out. These ones just continue in a straight line until they either hit something or land. IE, my fear is factual and based on current technology. As someone else in this thread pointed out, the engines aren't necessarily tested/certified the same way aircraft engines are. We don't have those guidelines for reliability, which means we can't be sure that engine failures will be that rare in UAVs.