Boss Media had single deck blackjack with considerably larger (0.15%) player edge for years. The game was removed only when people started botting it 24/7 for profit.
Did Betfair have a game with player edge which didn't involve any bonus? I haven't heard about that.
In the past, games with a small player edge lasted because most players gave the edge back to the casino through making mistakes. Once enough players figured out they could make money, the games got removed. This is probably down to the casinos being aware of what they were offering, and keeping a close eye on the overall performance of the game, so that as soon as they started making regular losses from it, they could remove it, rather than start voiding winnings.
The large expansion in the availabilty of "bots" has meant it is far more risky to offer a game with a player edge.
The Intercasino game will have players looking for a suitable bot to make the money before the mistake gets fixed, and if there isn't one available already, someone will produce one pretty quickly and sell it.
Betfair royally screwed up a promotion, and then compounded the error by making it "unlimited". Whilst it ran for less than a day, and most of this was overnight, it was possible to gain a HUGE player edge, and make money VERY quickly from it by using large bets, and continually recycling the winnings back into further claims of the "unlimited" offer.
One player made €32,000 at the cost of a night's sleep, and Betfair took the money back from his BANK 2 days after paying it out. THIS is where things REALLY went wrong for Betfair, and it was the way they dealt with the problem, rather than the problem itself, that put them in the rogue pit.