Dàjiā dōu zài jiābān, píng shénme tā kěyǐ zǎo zǒu?
Everyone is working overtime, so why should he get to leave early?
Tips
usage
Usually indignant: it challenges someone's right to do something and is much sharper than a neutral 为什么. It can also demand evidence: 你凭什么说是他干的? (what makes you say he did it?). 凭 means "based on; to rely on".