CSGO has actual humans watch replays to determine whether people were cheating, it's called overwatch. As can be seen, it doesn't actually stop cheating, at most it ensures that blatant ones are banned after the fact already happened.

You'll never see cheats banned in real time - that provides an enormous amount of data to cheat developers to allow them to quickly learn to evade your detection. Bans after the fact in large batches are the only sustainable way to go.