There is a good chance they don't even know what the price should be on the backend. The worst kind of apps are constantly running sales, special offer, limited discount, etc... Im pretty sure it's only calculated frontend side since it's very tied to if you just lost or if you are stuck in a game.

And tbh, I think they are okay with 10 hackers are ruining the game, as long as 1 thousand mothers are putting their credit card to pay for gems.