No one would legitimely create a site, invest hundreds of BTC, take the risk to lose everything... For nothing...
A site with 0% House edge is a scam.
Unless it's for example for the 1st week of launch of course.
How would they risk of losing everything if the house edge is 0%. Maybe if the house edge was against the casino.
However even then due to emotions, greed, and newbies using too much martingale, they can still come out ahead.
But I agree with you in general. Unless its some major site offering 0% house edge, it might be a scam and maybe not provably fair and scam users.