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U.S., like India, is a large country.
KLM does not allow guests with Business Class passengers. At one time KLM did not provide shower facilities to business class passengers, but did to Skyteam Elite Plus (Platiums from NW, DL and CO).
Golds from some airlines were Elite Plus too.
Are you talking about acesss for guests of a Business Class passnger, or those of Elites?
In Europe, lounge acess to Gold and above, on domestic flights os probably an incentive to lure people away from trains. Their domestic nerworks are not as large as those of the U.S. or India.
In Japan too, train is a competitor to airlines onany routes.