I think it's a bit of both.
"I probably would have voted if I didn't have to do that niggly enrolment and then go to a voting stall" was something I heard said by a few people. But on the other hand those people probably don't really know who they want to vote for or if they do are likely just 'sheeping' it.
How friggen hard is it to go in, check your name off and tick two boxes? I'd changed address, quote my previous one and my full name and bingo, I was given a voting slip. Not rocket science really.