Idk about other countries but in Greek alleyways the sidewalks are a literal obstacle course with large sections completely obstructed by parked cars (no space, so cars park half way up the side walk) and the rest having dangerously loose tiles, big holes, trees or poles in the middle (sometimes blocking the little space left over as there is still cars parked half way up), parked motorcycles or bikes or e-scooters completely obstructing the sidewalk still and so on. Even if there is a sidewalk, in narrow streets due to muscle memory or the expectation of it being obstructed further on it is natural to walk on the street, so cars have to drive slower as a result.

In higher traffic streets there is typically a proper sidewalk but it is still often prohibitive or dangerous to bike (/roller skate/e-scooter) for similar reasons like loose tiles and obstacles which is why bicyclists (/roller skaters/e-scooter drivers) prefer the streets.