Right. A lot of us have started carrying those, but not everyone. And even the slimmest ones have some bulk. I wouldn't carry more than one in a handbag unless I were leaving the house explicitly to shop for groceries. But sometimes you stop by the store for one thing on the way home and end up leaving with a lot more.
We keep them in the car or carry a collapsible one in a backpack, handbag, laptop bag, etc.