Originally Posted by
tmac-100
When I go shopping the prices in the various shops stay constant. The same is true when renting a room - whether it is a hotel (same price at the hotel for the same rooms) or a youth hostel, or with Airbnb - assuming the room is still available.
The issue with Avis is the same type of car at the same Melbourne agency WAS available - but the price kept going up.
What is there to understand about THAT car rental stupidity?

You clearly don't understand how things work in today's world. Plane tickets, hotel room rates, and rental car rates all change constantly based on demand and other factors. The is especially true of plane tickets and car rentals. If you find a rate you like, reserve it. Period.
I don't know about Australia, but in the US, you don't even need to pay to reserve a car, and there is no penalty for canceling.
Rant all you want, but that's the way the world works these days.