So firstly yes, dudes are just hanging out in front of the store, folks approach them, usually say something like “Trabajo? Tres workers?” or “Looking for a few workers for the day” And wait for a response, I assume a price is negotiated somehow but I’ve not heard that bit.

As far as flyers, most if not all of these folks are undocumented migrants, if they have a phone line it’s not a permanent one, and they also don’t want immigration enforcement to be able to trace them that way. You show up to Home Depot, get work and pay for the day and then move to the next job. Much less risk of being identified by the government.

As far as wasting time, from their perspective it’s a waste of time to be waiting around for a phone call when they could be at the spot where the contractor is going to be anyways for supplies