I have made some quite close friends of the people who I interact with daily -- coworkers, baristas, cashiers etc. In my experience the depth of intimacy available to you depends on how much you're willing to risk. If you reveal yourself first, other people feel more comfortable following your lead.
What you wrote about how relations with others can be expected to be shallow is, IMO, what the article talks about when the researcher says that you have to suspend the beliefs and assumptions you make when approaching other people.