Unfortunate for fast-food workers is that many of their jobs can be fully automated for less money than they are making now. A machine can make a Big Mac and fries to order and do it more precisely than a human. The net result of any wage increase would be the elimination of future McDonalds jobs. Sad to say, but that is the reality of it.
Automation would create some high-tech jobs to automate their stores, but many more low-skill jobs would be lost. Over time, to meet their demands, I think it would be about a million to a million and a half US jobs lost at McDonalds alone. The machines would then be exported, eliminating even more jobs overseas.
Now that they started striking, it will probably happen, anyway. Nobody is going to stand by at McDonalds and watch others take their business away because of pricing. They will simply keep the prices low by automating jobs. They have already automated much of the work at McDonalds. These strikes will only accelerate the automation.