If there's no sidewalks that's no issue for me. The law says I ride on the road so I ride on the road. In terms of family size that's no issue either, since they sell bike trailers. I see a lot of family units biking to my local farmers market and loading up with them, for example. Too much to push with your two legs? They sell cargo ebikes now too. The "grocery getter" car is obsolete.
Your point is valid, people drive short distances. But what if there are no sidewalks? Ive seen that too.