Coupon Uniticket 5 Stars

I need Advice:
hi guys there are several things I don’t understand in this game, and one of them is about 5 star uniticket coupons. What are they good for or better where do they exchange? you can’t in the shop. But it doesn’t make sense, why give them as rewards in champion fights if you can’t use them later?

Honestly I think it’s stupid that it is that way. They expect us to whale to get power ups or to beat Blue on Hard, So stupid