They actually check ID at many campgrounds and make sure it's the same person as the one reservation is made for. Generally they accept photo of reservation holder ID if (for example) you say that the person that reserved the campground will arrive later or got sick. Still pretty hard to impossible to scalp at scale - you can't change name in reservation, only cancel it (for fee).
They do not want to do auction because it will defeat purpose of camping be accessible to regular people. Outside of small number of highly popular campgrounds in prime season, you can book most campground in advance - very few campgrounds sells out in seconds.
This is the fallacious thinking that somehow market forces can be defeated at will. If they wanted camping to be accessible to regular (poor) people then they need to dole out those subsidies to them directly. If they sell permits below market rate then they are just randomly handing out subsidies.
They do not want to do auction because it will defeat purpose of camping be accessible to regular people. Outside of small number of highly popular campgrounds in prime season, you can book most campground in advance - very few campgrounds sells out in seconds.