Why are mental health professionals so easy to fool?

I think the point is that very few people are going to go out of their way to see a mental health professional just to fake something when it rarely works after being investigated by the courts. Also the only way they can tell for sure if someone is faking disability is to follow them around all day which is not their job to do. Its better to help several people who actually need it and let a couple people get away with benefits or drugs than to deny everyone who tries to get help for legitimate reasons.