I'm guessing it's also because there are significantly more elites with access to lounges at U.S. hotels as opposed to abroad. It's hard enough to get Hyatt top-tier status domestically, let alone internationally.

Additionally, Americans just don't demand good service. Look at breakfast. Almost all hotels, expensive and inexpensive, in Europe provide a continental breakfast. In the U.S., only the roadside limited-service hotels typically do this.