One of the most important patterns in third places is that the third place must define and delimit the zone of the activity that is the purported purpose of that space. There must be a place to serve drinks / lift weights / browse books as well as a space to *not* do those things.
Activity can be constituted in such a way that it anticipates its reception, and a functional space can be constituted in such a way that it organizes the space to receive that function.
So for example, a drive-through is kind of like a funhouse mirror of a third space. Drive-throughs serve the same explicit purposes as many third spaces, but because they don't permit for the patient, appreciative reception of the good or service, they do not support any form of culture.
Drive-ins are marginally closer, but not by much, because the space of reception at a drive-in is insulated from the audience by the layer of another space for reception, the car.
Sometimes you'll notice that people will subvert the intended organization of a place of commerce to create a space for reception. For example, even in crowded bookstores people will collectively shape little wedges to stand apart and take in something, or generate little wedges on which readers might perch themselves.