There's a big difference between taking advantage of pension tax reliefs in exactly the way a tax authority designed them to be used and creating an offshore subsidiary charging artificial royalties to exploit the tax authority's openness to actual foreign-owned businesses investing in the local area.

401K/IRA tax avoidance techniques are codified in law to encourage people to save for retirement so we don't have generations of elderly homeless people.

The tax loopholes that companies like Apple tax advantage of are another thing entirely.

>The tax loopholes that companies like Apple tax advantage of are another thing entirely.

No, the significant ones (i.e. offshore subsidiaries) are very much codified.

Letter of the law vs. spirit of the law.

Subsidiaries in countries with low tax rates certainly aren't against the spirit of the law.

Isn't the spirit to promote foreign investment, as opposed to domestic companies restructuring themselves to look foreign on paper?

I'd imagine it's more about not driving all the domestic companies away.