I think it is likely the decision of the site owner to decide what their edge is. Maybe one casino has less users and has to charge a higher fee in order to profit. It shows that shopping around can be beneficial when it comes to casinos. It also shows that Stake is a less costly place to gamble online.
This is why money pot investors lost a lot.
The affiliate % and bet back programs need to be adjusted according to the house edge.
i haven't played dice in awhile so my example will be off.
But moneypot and crypto-games was exploitable
Moneypot for example, you could set your house edge, open a site, and get 50% of the house edge that was wagered.
if you auto bet 1.02x payout. with 125% increase on loss, and 2% decrease on win....... you would eventually bust, but you would get more back from the reward program then the total amount lost.
If you set the house edge to 1%, you would need to roll under 97 "i think" 2% you would need to roll under 96. the reward ratio was the same, but you couldn't wager as much before busting.
the point is, with 1% it was exploitable, with 2% it wasn't. So a site with 1% house edge, needs to offer a less attractive affiliate/ betback %.
i don't play either, so i had to google "may be wrong" but it seems stake has 10% commission and the other has 50% commission, i think that's a big influence for the differences in house edge.
i don't think bchgames could compete with quality of games, so maybe they're focusing on attractive promotions.