question

i don't think the word is sarcastic in this sentence. to be sarcastic, it must mean the opposite of what the word usually means. cop is informal and it can be disrespectful compared to policeman, but since the woman is pushing back, she is not being respectful anyway, so cop is an acceptable word.

an example of sarcasm would be the woman telling the policeman, "thank you very much officer, i am so happy that i only have to pay this tiny fine instead of going to prison."