But even if you live 5-10 minutes from the supermarket many people will still drive because everything is designed around people driving. For example, it's very common to lack sidewalks and even when there are sidewalks, protected crossings can be sparse.
So a 10 minute walk to the store can involve you having to walk in the street or in the mud and grass, cutting across the street where there's no crossing signal, and having to walk through a busy parking lot to actually get to the building.
And even once you're in the store things are designed around cars. The size of packaging and the quantities that people normally buy in are based on the idea that Americans take their car to the grocery store once a week and fill their trunk space with groceries.