Serious environmentalists should be talking about flooding parts of the Sahara or other wild geoengineering prospects, not plastic bags at the grocery.
Serious environmentalists are talking about a lot more effective measures, although them being environmentalists (and somewhat realist) they usually shy away from pie-in-sky (desert) geoengineering projects. Examples are CO_2 trading schemes, phasing out ICEs, public transport, liveable cities, or reforestation.
Plastic straws/bags/etc are obviously small (but not necessarily negligible) efforts. They rise to prominence mostly because they are easy to mock.
I don't understand reforestation in the sense of plant X amount of trees, and feel good about yourself. Won't this happen naturally at a similar rate if you just leave it alone? I'm pretty sure my yard would be covered in different shrubs and trees within 10 years if I just stopped tending it.
Flooding the desert responsible for Atlantic hurricanes is ripe for unintended consequences. The planet is big and complicated, and everything is connected.
