Well, your take also seem pretty naive. Salaries in non-regulated jobs are a function of supply VS demand, that's pretty much all.
I would say office work does not actually pay more, it depends. Easy office-hand jobs probably pay much less than your previous job... but when it does pay more, it's simply because there's fewer people willing and capable of doing that job as a rate of the number of people actually needed for such tasks.
When a job is regulated (requires license, or is protected by some law etc) the equation is skewed, usually in favour of a profession.
I would say office work does not actually pay more, it depends. Easy office-hand jobs probably pay much less than your previous job... but when it does pay more, it's simply because there's fewer people willing and capable of doing that job as a rate of the number of people actually needed for such tasks.
When a job is regulated (requires license, or is protected by some law etc) the equation is skewed, usually in favour of a profession.