[foepys]

Because they are a member of the EU, a trade union that evolved into much more. They can choose to leave and also lose all their tech HQs that are only located there because Ireland is part of the EU.

[nradov]

That's simply false. The current EU membership terms don't grant it oversight of member state corporate tax rates.

[matt4077]

But it does provide for rather strict limits on subsidies, and a subsidy is indistinguishable (or, actually, defined as, among other things) making one-off tax deals with individual companies.