She called on us merely for the sake of courtesy.

她来访只是为了礼貌。

《新英汉大辞典》

Eg: Some companies acknowledge immediately the application letters from job applicants for the sake of courtesy.

有些公司出于礼貌在收到求职者的申请信后会马上告诉他们已收到信。

youdao

Pulling away is considered rude and "cold", so be prepared to sacrifice your own personal space for the sake of social courtesy.

说话时离得远被认为是无礼礼“冷漠”，所以，为了在社交时做到有礼貌要准备好牺牲自己的个人空间。

youdao

Where the law of the jungle takes precedence in everyday socio-economic affairs, societal norms of common courtesy and religious sentiments may also be cast aside in one way or another for the sake of survival.

FORBES: Exit Stage Left: Possible Societal Costs if the Economy Fails to Recover