Keno games are 100% fair thanks to the Random Number Generator (RNG) used by online casinos, and the keno machine that live casinos utilise. RNGs are complex programmes that are truly random, ensuring a safe and fair draw. An online casino would not ever consider rigging a keno game because there is too much at stake, plus it wins in the long run regardless of who else wins because of the house edge that is in play.
All the online keno casinos you read about on this website are fully licenced and regulated, which means they must provide fair games or lose their operating licence. This would mean they could not run keno but also all other casino games. The risk is not worth it.