Serious, Why does every 17 plus person complain of pain and general bodily problems now? They are always sick.

I work with over 100 people and every day it's always the young workers calling in sick or hurting. They also are constantly getting hurt at work. Like back and shoulder problems. The heaviest thing at work is a 20lb bag of bird seed which we don't deal with often. What bothers me is that they complain that they don't make enough money and then don't show up for work and then I tell them they missed all those hours and they gripe anyway. I told one guy that if he wanted more money he could work to make up the time he missed and he said "fuck it you oughta give it to me anyway". I just stared at him until he went back to work because I didn't know what to say. I just want some feedback.