The last stated income level was 100,000. Let's assume that for now just for discussion sake. What is the exchange rate in British sterling? Approximately 63,000/yr, correct? Does a family with 63,000 annual income fall into the 'rich' category in your country?

That one is a specious argument. The only time the exchange rate matters is when you are earning in one currency and traveling somewhere that uses a different currency. What I observed when Andy and I were living there, was that things seemed to cost about the same number. So I reckon that if you are earning pounds and living in England, 100K pounds will buy you in England what 100K USD will buy you over here.