Be it flying machines, watercraft or bicycles, there is an inherent arrogance in the state deciding which are worthy of having an uninvolved professional perform an independent evaluation before ANY operations are permitted. I shudder to think how the Wright brothers or Frank Whittle would have fared! Public endangerment is the issue, and that can be controlled by test area and test plan appproval. As experience is gained, then one can decide if (certification is desired) how to accomplish the validation tests using standard test instrumentation and methods.
I am a TP with almost three decades of actual development (a subject that most military TP's are totally unfamiliar with). In the States, an experimental airworthiness certificate, with test limits and area designation, is almost assured unless the aircraft is patently unsafe (unflyable is not an issue, believe it or not).