How street vendors tangle with the law in São Paulo, Brazil.With a little initiative and very little startup money, an outgoing individual might sell you a number of delights and conveniences familiar to city dwellers—from cold water bottles while you're sitting in traffic to a popsicle from a cart on a summer afternoon in the park. Such vendors form a significant share of the workforce in São Paulo, Brazil, but their ubiquity belies perpetual struggle. Some have t...