Everytime I hear someone lament about something not being thread safe, what I actually hear is - I want this shared invariant global state to be modifiable but

Everytime I hear someone lament about something not being thread safe, what I actually hear is - I want this shared invariant global state to be modifiable but it isn't. Which makes me ask the question why would you want that ? The process environment should not be the mechanism for threads to communicate with each other.