And I'll try one more time. Yes, each ball strike has a different cost depending on the ball. You are not, however, hitting that ball back to the original position.
What you are paying the extra hits for in this case is the mulligan, not the ball. You are paying for the opportunity to return a ball, no matter what type it is, to the original location. That should cost the same for everyone.
Whether you think it's worth the cost is not even related to the point that WGT is charging different people different prices for the same item.