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Join Date: Sep 2009
Location: Minneapolis: DL DM charter 2.3MM
Programs: A3*Gold, SPG Plat, HyattDiamond, MarriottPP, LHW exAccess, ICI, Raffles Amb, NW PE MM, TWA Gold MM
Posts: 100,373
In addition to the resort fees not being subject to taxes in some jurisdictions, I suspect that they're also not only exempt from earning points in some programs but also not eligible for travel agent and chain/booking service commissions.
Some organizations consider resort fees to be personal expenses on business trips and will not reimburse them, although there can be government or corporate rates that don't charge resort fees.