The one show stopper for you, been mentioned already but again now for posterity:
Security. <===
Your idea is fantastic, but to implement it you need some way to securely identify unique humans, a nontrivial problem.
Until we have this down, we will be wasting our time.
That is of course an interesting problem to solve. It would require keeping a national database with biometric data (actually the EU kind of has one - most of the passports nowadays are biometric). Of course, hackers could pose a problem, but with sufficiently strong encryption and a transparent mechanism open for public auditing, I think it should be ok. Just think the bitcoin system, which is relatively immune to tampering attempts because of its open source structure.