Promoting healthy participation in sports like football is a valid social objective, but restricting the rights of players for the purpose of producing more professional football players is highly dubious as a mater of national public policy. As far as I know, no one thinks it would make sense for my employer, the University of Michigan, to have to compensate Oxford University or Birkbeck College for the education they gave me, still less Raynes Park High School or Pelham Middle School. If we want more professors for the public good we use taxpayer money to subsidise education rather than imposing a specific tax on people who are already professors. But football is not governed by the state, it is a private activity governed by organizations such as FIFA and UEFA. IF these organizations, and their member clubs, want to promote the development of professional players they can agree on a system of taxing clubs to do so.
Um belo trecho deste artigo do Szymanski sobre o sistema de transferências no futebol europeu. Ah, sobre o Neymar, aqui.