There are two, slightly differing explanations. The Stardust’s gambling entitlement expired along with the building, hence no need for a "Trailer Station." As the Nevada Gaming Control Board’s Marie Bell explains, "This location closed in November 2006 and has not had gaming ... since then, therefore they would not be grandfathered and have to meet all current requirements," just like most other brand-new casinos. "Anyone who wanted to have a gaming license at that location would apply and go through the entire process," Bell elaborates. "If they applied for a non-restricted license, they would have to meet all current requirements, including minimum number of hotel rooms, etc., and whatever the local jurisdiction requires."
In this case, the local jurisdiction doesn’t require eight-hour casinos, which is why none are ever seen on the Strip. According to Boyd Gaming spokesman David Strow, the Strip is designated "a special gaming zone," unlike locals casinos which may abut residential neighborhoods, car dealerships, etc. So, if you’re the owner of, for instance, the old New Frontier site, there’s no pressure to develop, since the underlying gambling-enabled status of the land is there to stay.