Why do so many irish people support united & liverpool?

I recently visited Ireland and i was shocked to see just how many people were wearing celtic, united, liverpool, chelsea and even man city tops, while some of these people could have been visitors like me most of them wouldn't have been, and man city shirts? this is blatant gloryhunting, i know irish people have strong links with manchester and liverpool as cities but isn't it funny how united and liverpool are far better supported than everton and city? sorry for the rant but why do you think this is?