CVS treats it's employees like cr-p and that is reflected in the turn-over rate. They promise you 30 hours a week during flu-season then cut you down to 10 or less come spring because they couldn't care less how you're going to pay your rent. Thus the constant turn over, thus the lack of good, experienced workers in the company.
Couple that with the low pay and physical and mental toll of the job (because you're constantly running a skeleton crew because CVS is constantly cutting hours) and young people are the only ones stupid/inexperienced enough to take the job in the first place.
This is not the good old days of companies taking care of their employees and hard work being rewarded. CVS and companies like it are only looking to exploit and suck every dollar it can out of it's "human resource" and move on to the next poor sap just trying to make a living once the previous one has been all used up.
If you think the lowest level employees of an absolutely massive company are the cause and not a symptom of that company's failings then you may need to re-evaluate your perspective on some things..
@etxn+1lS2U0Th makes a great point.