Jevons Paradox is called a paradox because it is non-intuitive. It is very intuitive to conclude that when costs go up, people will use less of that thing.

I think it's a paradox in the same way that the non-reverse is. The spending might go down more than it's proportion of price increase.

An example not anchored in anything: If public transit costs x, I'll use it every day. If public transit suddenly costs 2x, I'm not gonna use it every other day, I'll rather find an alternative and use 0.