It is a shit tax that discriminates against SMEs in favour of multinationals. It is favoured by politicians as it appears to be a victimless tax. They would rather ignore the obvious weaknesses as the corporations shoulder the fall out. Corporation Tax only works effectively in a closed economy, or one where there is effective international co-operation rather than a race to the bottom zero rates.
There is nothing wrong with the tax itself, indeed it is essential.
The problem is with the nefarious methods deployed by multinationals to dodge their social responsibilities in not paying the correct levels of tax - and with the sort of corporate-stooge governments that dominate in western/developed countries, who allow the loopholes to remain wide open.
Until there is international cooperation on measures to counter this scandal, nothing can be done. And there will never be international cooperation because too many governments are under the influence/control of multinational corporations - the most in thrall being the US.
I used to have a pipe dream that the EU could be a 'force for social good', and part of this would the implementation of a uniform corporation tax rate, and with any multinational corporation having to pay tax on profits arising from each individual market (accounts dissected by tax lawyers to ensure compliance) and any non-EU corporation found not adhering to both letter & spirit of the laws would be subject to huge fines and tariffs on imports.
But the EU sadly fell under the control of the 'corporate elite' some years ago, and they're regrettably not much better than the US in terms of allowing corporations & banks to dictate policy.