A lot of anticheat methods are not to catch the people with the proper, premium cheating software. It's to stop little Jimmy downloading an exe for Fortnite because he loses too much and making a new account as f2p is now the norm. As such, a lot goes into making it hard to have a cheat hide itself without significant effort from the user, be that running a custom kernel module yourself or some sort of emulation techniques. The kernel level anticheats can naturally be bypassed, but you have to do more than just running an exe most of the time which is about as far as the average kid who downloads their cheats from a YouTube video is capable of. The result is you catch 99.9% of what would be cheaters, and that's a much bigger improvement to your player base than catching the 4 players at the pro level who pay thousands a month for custom software which doesn't really matter in the grand scheme of things.

You can still detect that stuff on the server. It's all about will and competence. The real reason is anticheat allows easy surveillance. The Ven diagram of people with Tencent anticheat and essential IT personnel overlaps a lot. This is a big problem talked about but not solved in sec ops.

Detecting the angle, acceleration and speed at multiple points of a shot in an fps is trivial, and developing a check to see if it's human movement or computer movement is easy after that.

Aimbots are easy too. Is the camera following someone without having vision? Oh no aimbot. A bit more complex than that... But not by much.

It's easy enough to do it right, but then you don't get that sweet sweet surveillance