I know exactly what it's like. I hear all this from my husband every day. I feel his pain and appreciate all that he does for our family. Just because I have never worked on an assembly line does not mean I don't understand. And what does having low seniority have to do with it. My husband knows people with less seniority then him that have way better jobs. You see, I do know a lot about his job. He and I have a great relationship and we talk. Therefore I do understand what he goes through every day. I'm not sure if you have a significant other but if you do maybe you need to communicate better.
As far as blowing your nose or going to the washroom my husband says you are wrong. It is the JOB of your group leader to releave you and let you do these things. If your group leader fails to do his job, than you need to talk to your Union rep. Do you know who your union rep is? If not, than you need to find out. If you need any other help, just let me know. My husband may have low seniority but he knows whats in his union contract.