You are wrong on all accounts, but that is perhaps the reason you are posting anonymously?
I don't know about Ireland, but as I am from Denmark, I know about the reason here.
Trust me, they don't get a tax break here, because no one does. Everything in Denmark revolves around 'paying taxes', even when a previous liberal government said they would halt the taxes, they didn't.
The reason, or one of the reasons, they chose Denmark was that we are a power-wise green country, and we can get a lot of power from surrounding countries if necessary. Last year 39% of electricity in Denmark came from windmills, and Sweden and Norway has a lot of waterpower that may be used on a not so windy day.
As a backup, German power is available, and they also have windmills.
The size of the data center will be 160,000m and they talk about a couple of hundred workers there.
That may not sound like much, but the effects on the local community could be large, as that may require people to stay there with families, requiring schools, public bus and train transportation, local shops, perhaps an upgraded local airport.
It may attract other domestic and foreign companies to put up a site in the neighborhood, because if Apple can do it, why not someone else?
So, it could eventually become thousands of people that are affected in a positive way by such a center.
The EU is always treating all companies the same, regardless of where they come from. And we do that because EU is still a rather loose organization of very distinct and independent countries.
You know, Fiat and Chrysler would be treated equal, oh sorry, Fiat bought Chrysler, so of course ;-)
Please let me know what EU based company has been able to do, that a US company was penalized for?