Short Answer: they haven’t needed it. Word of mouth drove the business.
And, most of the ads you’ve seen featuring Starbucks have been done by partners like Kraft and Pepsi promoting Starbucks ice cream, bottled Frappuccino, and whole beans, not ads for the stores.
CEO of Starbucks Howard Schultz always said, “Our stores are our billboard.”
I love the quote by Walt Disney that reads, “Do what you do so well that people can’t resist telling others about you.”
That’s what Starbucks was doing–something so well, you couldn’t help but bring a friend to your Starbucks if they were from a town that didn’t have one.