Sure, but the stated purpose of these bans was not to reduce the number of plastic bags we see, it was to reduce plastic pollution. That would make you think that plastic bags were the most important source of post-consumer plastic pollution, which they aren't — plastic packaging is. For marine microplastics ("the pacific garbage patch") the main sources are things like textiles, car tires, and of course fishing nets.

The thinking seems to be "well, it would be hard to eliminate those sources, so let's make it so you don't see as many plastic garbage bags drifting around, and it'll look like we did something meaningful."