If a lot is empty, there is no sidewalk there. Right now we have a few empty lots on my street, so the sidewalk does indeed just start and stop.
That's the most ridiculous thing I've read in some time.
The main ridiculous thing about what you quoted is that owners of vacant lots aren't being held to the same standard as owners of lots with houses on them.
Here's something
really ridiculous: Atlanta has a similar law (in theory), except it's a huge clusterfuck.
First of all, property owners are legally obligated to
maintain sidewalks, but not
install them where they don't exist (so if your property doesn't have one, you're golden!).
Second, there's been an ongoing lack of enforcement over the last 30 years or so, so there's a backlog of substandard sidewalks that would take (literally!) hundreds of millions of dollars to fix. This also means that most of the property owners with substandard sidewalks inherited the liability from previous owners, which is unfair.
Third, the same lack of enforcement also means that house flippers have been able to get away with just ripping out their sidewalks and failing to replace them.
Fourth, many of the poorer parts of the city have people on fixed-incomes who only can afford to live there because their homes are paid off; if the city enforced the law by putting a tax lien on them for the $4000 it would take to fix their sidewalks, they'd lose their home.