In my experience - there are a lot of organizations where old-school DBAs resist any modern software engineering practices, such as proper version control.
I think some of it is stubborness, but a lot of it is that DBAs in those organizations tend to be more "developers who happen to write DB code" and not really the A in DBA. Letting "their" code go into version control is the first step in breaking the illusion that they are somehow special, and it scares them.
Or it could be that DBAs who let the database go down get fired. I know a lot of DBAs that are old school that live in fear of any change because they get left holding the bag. They aren't special, they get blamed. It also doesn't help that a lot of new developers don't understand why "move fast, break things" is just not something any DBA of any worth is going to accept.
I think some of it is stubborness, but a lot of it is that DBAs in those organizations tend to be more "developers who happen to write DB code" and not really the A in DBA. Letting "their" code go into version control is the first step in breaking the illusion that they are somehow special, and it scares them.