Or, to give the movie its more accurate title:
My Name Doesn't Matter: Here's Furiosa Being Awesome.
Comments
This is a great movie. I was surprised you didn't comment on the Biblical imagery though - water from the rock, ritual anointing of warriors for the Holy One, leading people out of slavery, the Pharao's army coming after them with their chariots, searching for the Holy Land, etc. This is a much much better Exodus movie than the Exodus movie.
Now, for the ridiculousness:
a) Petrol is scarce, which makes it a display of power and wealth to drive these gas-guzzlers. It is the same thing that makes people buy a watch for $280,000 - it's a way of saying "Look how rich and powerful I am". And since gasoline apparently spoils after 6-12 months, there's no use in stockpiling it anyway.
b) Presumably the Immortan Joe turns on the water once per day and the people have to gather it up then.
c) Breast milk... well, it's richly symbolic. Joe provides them with mother's milk, he is their mother as well as their father. Presumably they eat other stuff as well. There was a Celtic ritual of patronage in the 6th century where the client had to suck on the patron's hairy man-nipple. Same symbolism.