Not all competing chains give a free room for free! For example, Triprewards best rate guarantee can get you a free room. However, some of their locations in US and Canada do charge a tax, while others don't.
Originally Posted by
iahphx
I have dashed off an email to Marriott customer service noting my belief that a "free night" should mean exactly that -- and pointing out that indeed it does at competing hotel chains. I'm not expecting much in response, but I will post what they say.