Unions here are really strong and it is the same in many European countries. The wast majority of people are unionized.
We do not have a minimum wage set by laws, but most employers are organized in a employer organization and the different trade unions make agreements with those organizations. So this then means most employers are bound by those agreements with set up like minimum wage, that a certain amount most be set aside for employee training, how hiring and firing is to be done and so on.
You mention McDonald's and in fact some two-three decades ago McDonalds, which back then was a new employer in Denmark, did not want to organize arguing that they provided fine conditions for their workers. The trade unions did not agree, so this then eventually became a "battle" where the unions would insist those organized was not to work with McDonald's - this then meant McDonald's found they could not get goods delivered, their trash removed and so on. These days McDonal's is organized and their emplyoes have all the things we take for granted ie. good pay, extra pay for working odd hours like evenings and weekends, a pension plan, paid sick days, long paid maternity leave, 37 hour work weeks...
Lots and lots of the jobs most today think of as skilled jobs is going to de done by AI when that technology mature, meaning when it becomes cheaper, better and so on. Those jobs will include most customer service support jobs not done in person, the cooking of food in fast food joints, many delivery and pick up jobs... so really we are gonna need to find other ways to earn a living or a system where those that not working gets not only money but also something meaningful to do.
As part of our social welfare system we do have the money thing covered for now. Anyone which is unable to work for some reason, gets money to still live a decent life here (we have very very few homeless people here). However when we imagine a future where much more is done by computers and thus many more not being needed in the workplace, the question is of course how can we finance the welfare system. For sure it will take a lot of radically different thinking and it will not be easy - but I think it will come easier in the places with really solid welfare systems.