[elAhmo]

Agree, it definitely is rude. Saying hello, good afternoon, responding to a question about cash/card also involves communication, and with earbuds it is simply rude to the other person.

If you don't want to talk to anyone, go to self-checkout or a vending machine, but cashiers are humans and not just robots scanning items.

[Hoodedcrow]

I see nobody saying "good afternoon" in a grocery store, that's the one place where you keep interactions to a minimum. Also, self-checkouts are not always an option because at least the ones at grocery stores here never accept cash.

[aiisjustanif]

Lived in DC and this is very true, lived in London and would be thinking about it all day if I ignored a cashier. London it is polite to say please, thank you, good afternoon, and all other verbal mannerisms.

[elAhmo]

Saying thank you to the bus driver in UK felt nice. Doesn't really hurt anybody.