Saying it's because of the currency is not only false, it's also stupid.
EU has dozens of problems:
-no common external policy
-no immigration policy
-no common taxation
-no common laws in general
-no common army
-no common executive
-no democratical system
Currency is just A PART of the problem.
Not the smallest one but still.
It seems that you have no idea or just hate the EU
OK I did a google and looked at the first hits
Immigration policy :
http://www.europarl.europa.eu/factsheets/en/sheet/152/immigration-policyTax policy :
https://europa.eu/european-union/topics/taxation_enTrue that tax is based on the local government. The local goverment pays the EU. It's just a different system.
In US you have state and federal taxes which is basically the same system except that the EU has simplified the system.
Common legislation :
https://eur-lex.europa.eu/browse/summaries.htmlCommon Army : No common army but our armies work together very well. This means all EU countries can work individually or as a team.
Common Executive : Nope we don't have an autocrat at the top. We have representatives in a european parlement.
EU is a democracy of democracies.
etc....