The event that had the single biggest positive effect on wages was the Black Plague. It effectively ended serfdom in Western Europe.
Bad example with McDonald's. A vast majority of their stores are owned by franchisees. If you sharply increase their costs, no one's going to want to be a McDonald's franchisee. Also, people go to McDonald's because it's cheap. If it's no longer one of the cheapest options, people will dine elsewhere. The only way these franchisees don't go bankrupt is if other fast food places simultaneously increase wages by a similar amount.