I don't know what the average number of uses for a reusable bag is, but it's certainly not one. We've got about a half dozen, including a few freezer bags that do most of the work, plus a few that have been repurposed as the "beach activities bag" and "kid's soccer stuff bag" and so on. The ones used for groceries have been used at least once a week for going on four years.

The old bags also averaged slightly over one use, but the mandatory "bag of bags" in the pantry got depleted much more slowly than it filled.

If someone is throwing their reusable bags in the landfill and getting new ones every time, they're using it wrong...which I admit isn't entirely their fault at this societal scale, but let's at least agree it's the expected way to use the tool.