Why are there different content policirs in different sites?

For example, homework-like questions are strongly discouraged on Physics SE and are immediately put on hold. Such questions however are asked a lot in Mathematics SE and are quickly answered. Why is there such a different content policy on the different sites?

Are the content policies standardized for all sites or are they decided by the site moderators?

Why are there different content policies on different sites?

For example: homework-like questions are strongly discouraged on Physics and are immediately put on hold. Such questions however are asked a lot in Mathematics and are quickly answered. Why is there such a different content policy on the different sites?

Are the content policies standardized for all sites or are they decided by the site moderators?