What you are supporting is local sustainability. The world would be better off with less global trade and more local productions. Local productions means a stronger community and more visibility for business practices, because it's more sustainable.

If a global business decides to just toss all the plastic it uses it in its backyard you'll never notice because it's 2000 miles away. If Amazon decides to treat their workers unfairly, you'll never notice. But you'll notice if a local business does it because you'll be walking in there every day. There's a level of accountability.