I grew up in a tourist area where >50% of houses were summer rental income properties. A significant chunk were furnishes with a set of cheap bikes and bike locks for the renters to use. So some significant percent of half of all houses there had 2-6 Walmart bikes.

The guy that has a massive collection of 1930s Scandanavian hunting rifles (or whatever other niche) skews the "average" gun owner stats. I would bet that similar outliers are at play for bikes since it's a similar case of some people use them as tools, a lot of people own a few, some people own a ton

Right now my family has 8 bikes in our garage for 3 people. All of them get ridden at one time or another depending on the specific activity. My 3 bikes include a folding bike for short errands around town or transit trips with a long transfer on one end, a mountain bike, and a skinny tire road bike for longer weekend rides. For families that ride, we are not that unusual.