Why is physical health and mental health treated so differently by society?

In the title.

The concept of mental illness isn't as wide-spread and ancient as are physical illnesses.
When someone is physically ill, they display visual, easy-to-quantify symptoms that are more often than not consistent with only one or two diseases, while mental illnesses can be an entire spectrum of different issues, which makes it less believable in the public eye.

Another contributing factor is that mental illnesses can be faked much more easily than physical illnesses, and, as mentioned, the concept has been around for a much shorter amount of time.

We can't say "My mind hurts." without everyone rolling their eyes, while we can say "my arm hurts" and someone will probably try to give you advice.

Mental illnesses are something not many people pay attention to, because unless they have it, they don't have to care, while anyone can get physically hurt pretty much literally everywhere.

In the title.

I think it partly has to do with not being able to 'see' a mental illness

Mental illness is not tangible and the vast majority of people are not psycho-analytical.

A bit of my opinion but even with an invisible physical illness which isn’t tangible there still seems to be Moreno stigma attached to having a mental illness.

Elaborate please.

I would disagree with the not being as 'old' as physical illness. You can trace back the history of mental health to Ancient Greek philosophy and medieval times where they saw mental illness as a curse or a moral issue.

Especially with males.

There still seems to be a lot of stigma attached to having a mental illness with longer waiting times to receive help than non-urgent physical conditions. People reacting differently if you tell them your on medication for a physical vs mental illness. I think I read an article in which 89% of people said they wouldn’t discuss a mental illness with their colleges which I’m going to take a guess and say is higher than those for physical conditions even invisible ones.

Not my experience at all. I won't discuss certain physical conditions I have because I'm usually met with "oh, is that it?" I even get that from so-called medical professionals. I've stopped seeking help for my vertigo because I've been told it's all in my head. Ugh.

I feel similarly. I hate having to tell new specialists for specialities other than rheumatology about my Ehlers-Danlos syndrome diagnosis because then they get their trainees to come in and then ask me to perform dumb tricks or show them my skin, or ask to touch my skin to show what they should look for in softness.

It's just weird. Makes me feel like a circus freak. Wish I didn't have to tell them about my EDS but it affects literally everything, so can't get around it.