Ed Whelan at National Review lays out the fact that Judge Posner believes that public opinion regards photo ID as voter suppression and one of his reasons for quasi-regret:

In his new book Reflections on Judging, Posner asserts that the
law is of “a type … now widely regarded as a means of voter suppression
rather than of fraud prevention.”

…The few words he writes—that the law “was a type of law now widely
regarded as a means of voter suppression rather than of fraud
prevention”—seem sloppy and ill-considered. In a book replete with
footnotes, he doesn’t bother to cite any support for his proposition.

Judge Poser wasn’t just sloppy, he is just plain wrong.  In this public opinion poll in 2012 on photo ID, over 73% of Americans believe Photo ID is non-discriminatory.  Of course, if all you listened to was academics and the media, you might believe that it was, but that assertion would be wrong.