Street tacos are usually served on a corn tortilla shell, not out of a bag. But they cost more.
If you are ever in Rapid City, SD, watch for a red truck for Malissa's Frybread near the parks. A Native American who makes excellent Indian Tacos. Instead of a tortilla shell, she makes them with Indian flatbread. They are so good! People from all over track her on FB to see where she will be set up next so they can get some.