Well then I suppose we are talking about the semantics of "atmosphere". I suppose we are arguing the same point but it's a matter of degrees.
Last time I checked Mars has an atmosphere, therefore a medium in which to produce lift/thrust.
The Earth has an atmosphere that contains multiple layer and extends up to 10,000km. One layer of our atmosphere is the Troposphere. It is the layer of Earth's atmosphere between the Mesosphere and Exosphere. I suppose you are factually correct to suggest there is "a medium in which to produce lift/thrust" in the Troposphere. As long as there are molecules for blades to push against, there is an opportunity for lift/thrust. But as I said in a previous post, I don't know if I would assume it would be simple to produce a craft to operate there.
I can't argue that Mars doesn't have an atmosphere. It does. That is fact. It's just a question of degrees. What I suggest is that Mar's atmosphere is thin enough that wandering about in it with a rotary craft is anything but "easy". In fact, I'm suggesting that the enterprise is difficult enough to ask the question, what is to be gained by doing so?https://en.wikipedia.org/wiki/Atmosphere
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