How come people don't give back positive comments when you give them, isn't it common courtesy?

Example, if you wish someone good luck on their new job or with their school, isn't it nice to provide that in return like, "I also wish you the best of luck with your decision in job-x or at school-x". I genuinely wish others well because its the kind and respectful thing to do.

How come people don't give back positive comments when you give them, isn't it common courtesy?
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