They are against voter disinfranchisement. The problem is that the IDs can be made harder for some to get than others.
See momocasa's post here: https://news.ycombinator.com/item?id=19879722
It doesn't seem to be catastrophic for New Zealand, for instance.
There's a strong argument to be made that people participating in the economy and other parts of civic life deserve to have a voice in politics. It's convenient and popular to exclude them, that doesn't make it just.
(I phrase my first paragraph the way I do because I haven't thought about it much and don't have a real clear opinion 'bout it)
On the topic of residents voting, a city near me had a policy+budget allocation vote that allowed anyone who lived there and was over 13. My opinion on that is that I think that's pretty neat at a city level, but I don't think it makes sense to allow non citizens to vote in a federal election.