Your outrage would be misdirected, as I have not patronized Starbucks in many years. But among friends who do, they absolutely feel pressure to tip, especially when they see the same barista every single day. I'll trust them over you, thanks.
I'm pretty damn skeptical of that, since in America the vast majority of customers do not put anything in counter tip jars. Maybe you've got some sort of strange selection bias going on...