I suspect the vast majority of people will have heard of it, looked up their car, found that it was compliant and now don't care.I think that is a misunderstanding of the actual situation. We won't of course know what effect it has had on the electorate in next year's Mayoral election, but recent reports have said that a majority of those living in the extended ULEZ zone are supportive of the scherme and its benefits. Once the rebel Conservative LAs failed in their court action, the whole thing became a done deal.
A lot of the "outcry" is from the media, I've heard a few with the misconception that they'd have to go electric rather than any modern petrol car complying.
Most of the complaints are people disgruntled that they'd have to change their car, though with the scrappage scheme and grants its gone quiet, and others who didn't like Sadiq Khan anyway.