The online casinos are fair, they use provably fair system to show their users they aren't scamming anyone. It's different from real casinos where you go to play. In this case I have no idea if they are legit or not because I don't have access to them where I live.
We need to care about it, because it's our money in risk, if you want to have chances to make profit by gambling you must care about it.
Remember that gambling normally makes people lose and that the house always has the advantage. It's difficult to earn a profit gambling and in the long run you will lose because the house has games that are never in your favor and the odds are against you. I have a question though. Despite having provably fair, how many people bother checking it on a website?