Even if you think that context isn't relevant, the premise of covid spread through surface contamination is still dubious. And even if that risk were credible, I assert that banning reusable bags would still be a dubious measure. Instead of using a grocery bag touched only by myself, they'd have me using grocery bags that have been touched by employees. Employees who've also touched my food, which I touched before them. Food which was probably touched by other customers before me. If surface contamination is a serious concern, the entire premise of a self-service grocery store is fucked and they should stop letting customers inside the store (self-service grocery stores are a 20th century invention; alternative schemes exist. Notably, self-service grocery stores weren't common until years after the Spanish Flu...) Since they haven't done that, it's impossible for me to take their bag ban seriously.