The horses were themselves a more immediate sanitation problem; in New York alone there was a million pounds of horse manure every day, plus thousands of horses that dropped dead from overwork. Disposing of all the feces and corpses was a challenge.
And to be fair there was a lot of grumbling about the "horseless carriage" for quite awhile.
What's interesting to me is that the oldest streets (ignoring the Main Street) in the local small town are the widest, because they needed to be able to turn around a team of horses and a carriage/wagon even when other wagons are parked on the side. The newer streets (but still 1940-50s) around are narrower because they didn't have to accommodate that.