I work in logistics, warehouse management systems (in particular the one I've specialized in) have incredibly complex databases with a lot of business logic baked in. This is due to being very data-crentric applications.

Also, in many non-tech companies the database admins were historically a consistent IT resource even when no other developers were available, so SQL gets leveraged extensively. When your only tool is a hammer, most of your problems end up being weirdly nail shaped.