Assuming Irish tax collections aren't idiots either one of those companies owns all the shell companies - or those "independent" companies will be cooperating in a very anti-trust vulnerable manner.

It doesn’t matter if they are idiots or not. The only thing that matters is whether they care.

Probably not, which means that the game of tax competition just became less transparent.

Sure, the headline rate may now be 15%, but so what if the tax collectors don’t care?

Besides it’d probably still be significantly cheaper for companies to pay the fine for any “alleged wrongdoing” than to pay the headline tax rate.