Being a CNA is not easy, it is tough work. If you get yourself all twisted around about other's motivations and/or behaviors, you will burn out in no time. Hence why perhaps your Dad felt that at that rate, you would be stressed and discouraged pretty quick.
Do what you can to learn what you need to. Work to make your patient load comfortable. What others do, don't do, why they are there is left up to them.
That is wonderful that your work ethic is a good one. Your Dad, I am sure, is proud of those things he instilled in you. Look at this as a stepping stone to really be in a place where you can look at all of the different ways one can advocate for a patient. You may want to go to nursing school
. You may want to go into social work or case management. Or you may be quite pleased with the patient interaction that a CNA has, and be happy in your own duties.
Whatever you decide, make a pact with yourself that you can not change someone else's behavior. Go in, do what you can, and leave the rest.