Didnt we have the same situation with the French in the recent election, there is so much of a French vote here that even Francois Hollande himself came here to woo the voter. Some nationals take more of a home grown interest than others...Americans come to mind in particular. I dont know about you but if I was champagning it on the Cote D-Azur on a permanent basis, i wouldnt be too concerned about who was getting elected in Dublin South.
I imagine the Brits are the same.
Not sure how taxing overseas earnings would work re the US system mentioned. The inland Revenue here are interested in all our overseas earnings, but unless these Americans have assets at home surely they would just be taxed under the British system.