I grew up on G street between 11th and 12th.  Back in the 50's and early 60's, it was each homeowner's responsibility to clear the sidewalk paralleling the street in front of their respective house.  I don't know if that was an ordinance or a collective civic agreement to do one's part.  I was a kid and I had my chores and that was one of them.  Everybody in the neighborhood shoveled their walks including the sidewalk paralleling the street.  There was no resentment about it being "free" shoveling, we just did it.  In the present day, long stretches of sidewalk paralleling long stretches with no housing or multi-unit housing is another matter and should be covered by taxes as a collective responsibility.  Everything back then was downtown and the city was accessible by walking.