Re: Profits = tax bills?
I'm not too sure on your question, but in general...
A company is taxed upon its profits in the country where those profits are recognised.
If you make £100 in a country with a corporation tax rate of 80%, then you hand over £80 to that government. You may notice that the next door country only charges 5%. So you open another company in that country, and send a bill for "licensing" or "management fees" to the first company of £99.99. Now the first company makes a profit of 1p, which is taxed at 80%. Good luck collecting that. The other company (assuming it has no other costs) has a profit of £99.99, and pays tax at 5% (so about £5). Total tax bill - about a fiver. Would you rather pay £80 in tax or £5?
That's sort of what Amazon, Starbucks et al stand accused of in the UK, and that's probably why you describe them as efficient. They use low taxation regimes to pool profit, reducing the overall tax bill. Sort-of. it's far more complicated than that, but you should get the gist of it.
Amazon made a loss last year. Losses are not taxed, in that you don't get tax back if you make a loss, but you (in many jurisdictions) carry the loss forward to net off against your future profits, reducing your future tax bill.
Does that make any sense?
Otherwise "efficiency" could mean sales per $ of capital (it's called an efficiency ratio).