No, it's the exact same reason every monopoly or cartel doesn't constantly raise their prices - a combination of topping out what the market can/will pay for the product (car travel in the US went down markedly over the spring & summer because gas was too expensive) and also wanting to stay "below the radar" because when consumers finally realize how they're being played they tend to demand action from their government.

This has all been studied extensively in economics & understood for generations now. Again, it ain't rocket science.