click vegetbale- I think you need to take a step back for a second and breathe. What you did just now seems to be a rant on how you were feeling in the moment (and clearly after many moments like this you sort of just burst).
While everyone should and is entitled to their moements of outbreak, you should reevalute what you just said. I will give you my approach to any worker in any store including grocery stores. I Baruch Hashem am not the frustrated type, therefore I dont mind long lines, even when Im short on time. I just make the best of every situation. In life you will come across people who annoy you and challenge your personal issues (like anger, impatience etc.) It is important that you take time out of your life to recognize these issues and learn to work on them, so when you are in contact with someone in a grocery store, you are able to handle youself and come out stronger and less frustrated. People who work in grocery stores do not want to be there. I came across a lady behind a counter today who was exhasted and did not want to be anywhere but there. You need to feel for the workers, it is not an ideal for them. So yes it can be frustrating, but make these people feel btr, give them a smile, give them some words of encouragment. And seriously, don’t feel bad if it frustrates you, cuz ur entitlated, but Hashem is sending you a message that this is an area you must be working on!
I hope this helps!