It's a major money maker for them! I only do the mini-bar for soda or nuts now if for some reason I'm desperate/didn't get a chance to eat, especially in the UK where the GPB kicks the $$ butt. If there's a shop nearby, I'll pick up water, etc there.
BTW - anytime I've gotten anything from the mini-bar on the last night, if I didn't mention it at check-out, always showed up as a sep additional charge on my credit card bill (usually after expense report submitted). I've never had them not show. And one time it took 9 months to get a credit when I had mentioned & paid for it at checkout & then got billed again after the fact.
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Sharon