https://www.merriam-webster.com/dictionary/protest :
> the act of objecting or a gesture of disapproval
> a complaint, objection, or display of unwillingness usually to an idea or a course of action
On a more serious note, I wonder just how people end up with unpleasantness being the standard go-to behaviour when people behind the counter aren't just giving them what they want.
Surely at some point in their lives they must have noticed that being polite and pleasant is far more likely to get you what you want than acting like a dick?
Usually the guy behind the counter has no say on company policy, and going against it is very much not in their interest. They'll be even less inclined to breaking policy over someone that acts like an asshole
In general, I think it's unfair to ask a probably-underpaid cashier to break policy in this way -- they almost certainly have no control over the policy, and quite possibly face severe consequences if they acquiesce.
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The probably-underpaid people who break policy make the world go around. We'd get nothing real done if people just followed policy all day long.
It might sound like I'm joking, but I don't. I have huge amounts of respect for those people, and obviously if they help me out I will do what I can to help them out. (Even if it's just paying it forward and breaking policy when necessary myself.)
I'm not anti-policy. I love good policy, and I rarely have reason to break it. The policy that often needs breaking is the bad policy.
Some advice you never asked for: in that situation, protesting often makes things worse. Learning a little bit of negotiation and sales is an invaluable investment in life.
A simple you seem concerned about selling this to the wrong people / I'm about to make your day a little bit more difficult / you probably think I'm being unreasonable / is it absolutely impossible for me to come home with the medication my wife expects me to? / I don't want you to do something you're uncomfortable with / how can I explain this to my wife? can go a long way.