Why is the voter turnout in elections for the European Parliament so low?

The most likely explanation for this is that voters in the
countries of the European Union do not care enough about their government to feel that
there is any benefit to getting out and voting.  This is likely due to the fact that the
EU government does not have very clearly understood roles in people's
lives.

People tend to turn out to vote when they feel that
their vote can have an impact on their lives.  This is not generally the case in EU
elections.  The EU government is a relatively opaque entity that is far away from the
people and whose impact on the people is not completely clear.  People do not understand
very well the ways in which the EU government can affect their lives.  Because of this,
they do not think that EU elections are very important and they do not, therefore, turn
out to vote.