Re: It's not about fair, it's about the law
Going after sweetheart deals is the best way to get coherent and cooperative international tax policy.
Sweetheart deals are are a form of state aid. As such they are generally tolerated as long as they are open to all and have clear limitations. Are you seriously arguing that a deal cut between Apple and Ireland in 1991 for preferential treatment, in order to offset the costs of setting up business in Ireland, should still apply today?
In any case, the real bone of contention is that Apple setup a shell company in Ireland for handling international sales to its subsidiaries but thinks that this shell company should somehow be exempt from even Ireland's low corporate tax rate. So, apparently it's okay to pay corporate tax on business done in Ireland, but apparently not okay to pay corporate tax on business done elsewhere in the EU. In which case, the alternative is surely that Apple should pay the tax (presumably at much higher rates) in the relevant countries.
The single market exists precisely to avoid this kind of complex accounting and even allows them to play countries off against each other but they must pay tax on all the sales in the EU as a result.