Why doesn't netflix upload all seasons?

There are sooo many (anime) series that still have sequels, but why doesn't Netflix post these sequels? Zbs my hero academia has already released 4 seasons, but only one season will be broadcast. : /

Because netflix does not have the licenses, or it is not worth buying them

This has something to do with rights holders, that's not so easy with anime in DE. There's also a wait until these seasons are available in German. And who knows who has any exclusive rights to what. The streaming providers also try to harm each other.