Tokyo requires that car owners prove they have a reserved parking stall before allowing them to register a vehicle. That takes care of sidewalk parking.
But the easiest way to eliminate sidewalk parking is to install meters on the street spaces. Then the local authorities will promptly tow sidewalk parkers for meter evasion. The problem only crops up where parking is mandated and free.
Leys see how that works out on counties with corruption endemic at low levels of enforcement.
Mexico City had no parking meters six years ago and a serious sidewalk parking problem. As the new meters go into neighborhoods, the local parking cops (on bicycles with a trailer full of Denver boots) detain illegal parkers.
It works absolutely great. The neighborhood has new cash to spend on improvements and there's legal space to park in for a price.
Speaking of low parking slot cities, ever enjoy having sidewalks and pavement taken up by parked cars. Slots or not, people park their cars.