It's not that devs and DBAs don't care, it's that in many cases (not all) they aren't given the time to carefully test the system to see how it might be abused.
And also, many companies view security testing as an afterthought or an audit requirement. If they do not have to do it (time is money) they won't. And when they are forced to do it, they rush through it.
In some ways this is a philosophical fight between a group that wants to ship software and make a profit and a group that wants to design and test systems to make sure they are correct. Suits vs technologists.