I worked nights at a McDonalds about 4 years back (first year of university) in Canada. You are spot-on about them treating humans as the weakest link.
For instance, I noticed that every carton in the freezer contains an illustration of the item inside (in addition to names in English and French). My understanding is that they simply do not trust their workforce to be able to read the contents of the carton and will gladly slap an image on top to remove any unpredictability from the process.