It's not so much a bonus specifically for hiring minors, but there are lots of ways in which minors are less expensive. Because of labor laws and schedule conflicts with school they usually won't be able to work enough hours to qualify for full benefits. They also tend to be much more tolerant of poor working conditions because this is usually their first job and they don't know any better.

Omg I once covered at this store not to long ago that practically all their workers were green beans. I was the veteran there even though I have only worked for Starbucks for a year and a couple month. I know it wasn’t the green beans fault but I had to practically solo bar during peak at a very busy store and keep helping green beans on register and drive thru because they didn’t know what to do and the shift in charge wasn’t very helpful while I was getting flooded with drinks and trying to keep the store in control, the shift decided just to chill in the back the whole time. Then when I asked the green beans if they can help in bar they told me that the manager skipped their training -_-. Essentially the choice was to solo bar and carry that store on my back or have the green beans help in bar but slow me down because of having to explain everything

I’m failing to see what this post has to do with minors?