Now something like this is bound to come, from the new treaty, to all G7 countries, which hopefully means it will trickle down to the G20 at the least.
The main issue is not rules on sales though - it's cracking down on profit-shifting masqueraded as IP transfers and licensing. Hopefully that too is being cracked down on.
Apple revenues in the UK was about $2B. Which means Apple is already paying $360mil in GST tax to the UK gov. Apple also paid some amount of wage, income, real-estate and other taxes.
Let's imagine companies had to pay income tax on a pro-rated, point-of-sales basis. Thus, apple's pre-tax income for the UK would be 2/274 * 67 = $500M. At a 20% income tax rate, this would net the UK gov an additional $100M.
This is why they want this sort of thing. It has nothing to do with fairness. The US gov is generally opposed to pro-rating profits based on location of sales. Because the US tax code allows companies to effectively deduct foreign taxes from net income, income taxes paid overseas has the effect of reducing income tax paid to the US gov.
No, GST is a VAT (in fact, the UK’s is called a VAT, not a GST), which is not the same as a revenue tax.
The end result is, the consumer pays VAT which is 20% of the price (i.e. 20% of the revenue), and the tax is spread out evenly across the whole production supply chain, weighted by the amount of added value by each company in the chain.