The way I have always understood it, the main issue with plastic bags is that they are very difficult to recycle and they do not break down easily, so they end

The way I have always understood it, the main issue with plastic bags is that they are very difficult to recycle and they do not break down easily, so they end up polluting the environment. As for the "amount of water and energy spent" to produce them, yes, that is tiny compared to something like a tote bag (and for most commodities, production cost usually tracks closely with resource use). But in a sense, that is actually part of the problem: they are so cheap and resource-light to make that they get treated as disposable, and their environmental cost shows up later in waste and pollution rather than up front in production. Generally speaking, when I was younger (say, 20 years ago), discussions about environmental impact were almost entirely framed around pollution (what ends up in the soil, air, or water), not around the energy footprint of making things. It's interesting how it changes nowadays.