"Tow-hitch receiver" Could just mean its ready to recieve a tow hitch
Lexus seems about one production year behind releasing hitches. it was over 6 months before you could get an RX330 Hitch from the factory, and about the same if not more for the GX hitch. (I think it was same story when the RX300 came out too, not sure!)
Horribly handled, you would think that by now they would have it down. Listing tow specs and have no hitch available at point of sale is a shame