The point is, why would they bother even with the minute hassle of vetting and hiring an agency just to make a few pennies every year as compared to their exist

The point is, why would they bother even with the minute hassle of vetting and hiring an agency just to make a few pennies every year as compared to their existing billions? It's not even worth their time to do that much, apparently, since the houses in question are sitting empty in a high-rent area.