The SaaS wants to extract as much value as possible. They don't know YOUR individual use case or threshold, but they need to price in a general way so that based on the model of reality, the most revenue will come in (+ whatever other goals).

You want to get as much value as possible.

If they know that you use it twice a year, they could offer you a special price. But doing that for just you might be not worth the extra code in their licensing and usage tracking system. So there needs to be lots of you.

In addition there could be high paying whale users happy to pay a lot and only use it twice a year.

So they need to know how tight/loose each customer is, in addition to what they want, to come up with appropriate pricing.

It would be like a bazaar where the price for a vase is 1000 but locals will haggle it down to 100, expats will get it for 150, tourists that haggle get it down to 250, and naive tourists pay 1000, the full price. And the seller can look at them, their body language, the look in their eyes, and judge the price accordingly.

AI might get us there!