There are several short-line railroad companies that operate spurs and industrial-park operations just like this one, often paid for by the "park" developer and owner (most of those warehouses are leased, not owned, by the users). UP's main involvement may be to deliver strings of cars for the site and pick up - perhaps even pre-blocked - outbound cars, with no on-site work. While not ideal under PSR, it's a lot better than loose-car railroading. See, for instance, McClellan Park near Sacramento.