For instance, there are times where the choice is wholly ours. Eggs, for instance, often come in plastic or cardboard, so aside from taking a few extra seconds to consider the kind of eggs we want, that's easy. If we want yogurt, though, we basically have little choice beyond considering the packaging that wastes the least plastic.
But there's still so much we can do. When we know that a store puts plastic utensils in an order without asking, and/or gives us our purchase in a plastic bag, it's simple to ask them for neither. It's also simple to carry a reusable bag or two, or a travel mug, et cetera.
Spending just a little energy can easily reduce default plastic use quite a lot. This story is a good reminder that perfect should never be the enemy of good, so at very least we should try where we can.