Many are, somewhat. It’s common for services to have different overage rates at different tiers (eg: starter might be $10/m for 10GB and $0.1/GB after, while pro might be $50/m for 100GB and $0.01/GB after).
They also tend to differentiate on other features and support levels too, which muddies it a little, but the concept is there.
They also tend to differentiate on other features and support levels too, which muddies it a little, but the concept is there.