Actually, at least based on my area, McDonald's seems to be careful about hiring, or at least careful about not letting bad service creep in.

The food and overall experience is... fine, and you go there because you want food and you want it with little to no hassle and get the food reasonably quickly and expect them to get the order right. If the service is bad, then I'm going pretty much anywhere else, McDonald's is not worth putting up with crap service. A poor hiring practice coming around would tank the only reason to go there.

There are a number of other fast food places in the area I would tend to prefer, but avoid because their service just sucks, the order taker somehow not knowing the item you are ordering is on the menu, taking an eternity to make orders, and getting the orders wrong in the end, and then things like the fried food clearly being cooked in oil that needed to be changed a few batches ago. I've seen what poor hiring practices can do to a 'good' restaurant, I can only imagine what it would do if McDonald's had that problem.