I’m pretty sure all real fight companies pay win bonuses
I don't know for sure either way but I highly doubt if Fighting Dolls or Foxy Combat do.
But that is actually besides the point. It would help producers if they told the customer if they do.
First of all: I highly love the idea that the "winner takes it all". I have seen matches at live events where a guest sponsored a victory bonus. But, here the problem starts.
If you are a producer you need to pay the same amount for the same fight. It is like in sports: You will not have a sustainable business, if you dont pay the same. Look at the english premier league. Always the same clubs at the top. Totally boring.
As a producer your bigget value is your team. You spend half of your time in getting new fighters. You will not risk this by paying unequal. The girls will find out. And then you have an issue...
I dont know any producer who pays unequal. There are only some guests who do victory bonuses. But, this is even dangerous, because girls might fight harder than wanted. This can result in injuries, and nobody wants this. As I said in the beginning, I have seen this. It might look good for guys. But, as a producer you dont want to risk this. So, tbh, the only solution would be to make the customer believe that "the winner takes it all".
