In the interests of accuracy in these debates
1. So many people still natter on about the price of petrol per GALLON, especially in the American context. Why? Perhaps most are unaware that an American gallon is significantly smaller than an Imperial gallon:
1 US gallon = 3.7854118 litres
1 Imperial gallon = 4.54609188 litres
So simplistically saying a price per gallon does not translate so easily.
May I suggest moving forward to the last century and using metric measurements (even I, late fifties, had to use the metric system for most of my school days).
2. A pound/dollar per day. What does that mean? A pound a day in Europe would barely fetch a bar of chocolate. In much of the "third world" it would buy a full evening meal of good quality. What a foolish way to assess poverty or wealth.
How about working time to pay for family meal or something?