Say a company is globally headed in the US. It has a UK branch. It makes money from sales in the UK branch. It pays tax on that money. It then repatriates the money to the US (where the shareholders who want the money are). This is an income stream which also attracts tax in the US. Is it fair to pay tax twice?
Next: say you buy something from a company in a foreign country and it is delivered to you in the UK. Should the company pay tax on this in the UK? It is already paying this in the foreign country. This is the situation you have with Amazon. However it is true they are delivering ahead of (and in anticipation of) the actual orders so you get your product more quickly. Does this make the difference? If so they could just wait until you've made your order - the only difference then is that it takes longer to receive your product. How does that help anyone?
LB, you really are a massive geek.