Safety is the issue, model aircraft(whatever shape or size) operating in airspace which places full scale aircraft and human life at risk. Am I wrong? Where was it recently where they arrested folks for pointing green lasers at aircraft, law enforcement can't enforce model aircraft flying in restricted airspace? That is where the problem is and that is where it needs to be enforced, sending LEO's to check if model aircraft are registered at a long term established flying field is a poor use of resources and does zip, nada, zero, the big goose egg, etc. increasing safety in the NAS.