Like they already said, it's either true ignorance or it's a deliberate choice of wilful ignorance - or it's a conscious decision to feign ignorance. The latter is something that a lot of people do in order to escape accountability for their beliefs, and that has to be taken into consideration, and the previous comment didn't mention that possibility.

If someone doesn't know enough about an issue to care and also doesn't know the things that would motivate them to find out more about the issue that would make them care, that is true ignorance.

If someone doesn't know about an issue and deliberately avoids exposing themselves to things that would care, then it's a deliberate choice.