> If everywhere had the same tax levels, why would anyone bother to be resident anywhere other than the London/New York/Tokyo.

My question is, why would I ever want to be resident in any of those places? Never in my life have I ever considered living there. I barely tolerated San Jose for 9 months before I moved to Santa Clara.

There are plenty of reasons to live outside megacities, taxes are way down on the list.

If you're a huge multinational, megacities have a lot of advantages.

> A tax cartel probably won't happen - it is against many governments' interests.

This is a variant of my argument. I may add: It is against many governments' _perceived_ interests. I do not think that a race to the bottom (Come here, 15% tax! No, here 10%! No, here 5%! ...) will help any government in the long term. So far, I seem to be correct.

No, it's against their actual interests. As I said above, if all countries charged the same tax level, no one would bother to reside in the ROI for tax purposes. Ireland has a strong interest in tax competition. Whatever money they gain from Apple is money they wouldn't have otherwise.

Because the cost of living (food, residence, etc.) would go up to match demand?

I'm talking about residence for tax purposes, not real residence.