Is it normal i hate when people say something is subjective like psychology?

I wouldn't go as far as to say it's a scam. Clinical psychology is definitely not perfect and clients should be aware that their professionals are fallible.

It might not be fair to hold clinical psychology to the standard of physiological health, as we do instinctively, because we know objectively a lot more about our bodies than we do our minds. It might be more fair to compare the underlying theory of psychology to theory in all the other sciences. In every science there are a large number of contentious debates, a large amount of subjective knowledge. Most people don't have any care about the gaps in objective knowledge in particle physics, but because of the nature of the application of psychology the gaps in objective knowledge here trickle down in a way more people will notice: into the clinical world and real people's lives.

As long as there is evidence that all the different perspectives in psychology hold clinical value, which they do, I think we should embrace the lack of homogeneity in clinical professionals.

The reason you can't use a computer is often because an individual won't judge themselves correctly. I.e. thinking about yourself is generally not an emotionless matter, emotions and your own feelings get in the way unlike a professional who should remained detached. For example, a paranoid schitzophrenic person experiencing hallucinations may not view them as such because, for them, they may almost seem more real than reality itself. More so if the illness is severe enough because then wouldn't even be capable of entering their own symptoms into a computer. They would need to be judged by a psychologist.

Also, I'd like to see some evidence for this statement you're throwing out that it'll "never be the same". In clear cut cases, that's certainly untrue. Results will only differ when the individual's illness isn't very severe or is mixed in with another illness/extraneous variables which may've influenced the difference. Often patients may tell another psychologist something they didn't tell another which leads to a different diagnosis (e.g. certain illnesses are more common because of poor parenting so if a patient only expressed this to a partial extent to one psychologist but a full extent to another, it may lead to changes in their diagnosis).

But I do agree with you on sessions. Symptoms can change depending on how much stress someone is undergoing at the time of the session (which often makes the illness worse ten fold) which can affect what the thought diagnosis was.

Exactly! That's a good way of describing it :)

In the case of the car there can only be one right answer as to what is causing the noise, even if there are two things causing the hissing noise at once (comorbidity). We can have true objective knowledge about the problems of the car. Mental health might be more complicated; we're a long way from objectively knowing everything about what makes us do anything, and it's possible that even if two different disorder labels are given they could still both be accurately describing the exact same condition from different perspectives. Classifications for disorders, and the existence of specific disorders entirely, change all the time because mental health disorders are a social construction.

Sorry, I phrased it badly. I didn't mean to single out psychology against other science. What I meant is:

Do you think science is objective?