Some jobs are not meant to be the kind of jobs that pay you a living wage.
Such as Mcd's for example, most of their employees are first time jobbers, students and people that want to work part time. Most of their full time employees are generally managers or people that are just stuck in life and didn't better themselves.
If you take all those unskilled people with low paid jobs in every industry, and raise prices to pay them a "living wage", you are just raising the cost of living for everybody. Which defeats the purpose.
Many business wont survive and many people will become unemployed. As if business can just raise prices without consequences.
I used to run a small ebay business/store from my bedroom many many years ago when I recently finished my studies. I quickly realised how to price my items so they could sell fast and what price it would take ages to sell them, and what price they would never sell. It was so basic, yet an elementary understanding of how markets work and how to make money. I couldnt just buy any item and list them on ebay with a mark up and expect them to sell. no no no, that was nearly a sure way to lose money and get stuck with something that I couldn't liquidate. This is just basic business.
Prosperous countries have free market economies and that is just one reason why they are prosperous.
Every country has its rich and poor but poverty is more prevalent in countries where there isnt a free market economy.