If it was just too much work to pipe the overflow into the pan, then why bother wiring up the float switch? What you cant see is the main drain line runs uphill after going under the unit and the drain pan itself isn't piped outside. The saddest part is this unit was installed by one of the better contractors in the area and inspected by the county. The inspector had noted with a red pen on the duct work that there was a screw missing at the heat shield but failed to notice what you see below. What a shame.