Google isn't making arbitrary decisions here - it's reflecting social norms. Americans aren't big on walking. I've seen pictures of beautiful leafy suburbs that don't even have sidewalks.
https://www.statista.com/statistics/747380/daily-step-averag...
The difference is: they COULD walk if they wanted.
You can't if there is no walkway.
The other scenario of no sidewalk are like rural roads that are very long with nothing in between. So there sorta "no place to walk to".