Irish citizens may vote at every election and referendum. provided they are registered
British citizens may vote in Dail Elections, European Elections, Local Government elections, provided they are registered.
Other European Citizens (Eu) may vote at Government and Local elections, unless they have become Irish Citizens, provided they are registered.
Non EU citizens may vote at local elections only, provided they are registered.
I'd like to believe that it's a genuine mistake on those sending out polling cards, in that they are confusing the rules, i.e. the rules which apply differ between Local Government and Dail Elections.
A person completing a Registration form for members of a household is obliged to sign and date the form!!! Wonder if these signatures are recorded anywhere???.