Atco94
Standardization :
It is what an average controller can adhere to or provide services almost always.<Though I also believe that some are definitely better & few excellent ones & particularly He/She(may be Me or myself) is always the best controller( that is the saddest part of ATC profession).>
as singapurcanac says about security isuues :
when the airlines of one country can fly in another country or the flight/ground crews can move about freely between diverse national carriers without any problem(security or otherwise) then I belive it is not the issue.But it is quite possible that it is may be my "issues"?
Though traffic density at different places might be different but as most of us will agree ATCOs are the most flexible at their work & can really adapt to a new situation quickly & efficiently.