I had the same thought. Not bashing their work I am genuinely curios.

For this specific case I was suprised to see they have a dedicated website for such questions! So I guess it is quite common.... (They seem very serious about it since i couldn't even mark the text to copy it here! )

>Tolkien’s original drawings, paintings, maps, designs, scripts and other graphic works are protected by copyright and may not be copied. The Tolkien Estate takes action against parties who try to commercialise Tolkien’s works, including maps of Middle-earth, the One Ring Inscription and other images.

[0] https://www.tolkienestate.com/frequently-asked-questions-and...

The key is that the original maps are copyrighted, and direct derivatives may fall under that, too - but the general information cannot be copyrighted (at least in the USA).

You could make a freeway map of Eriador, for example.

And see all the "unofficial" books around Minecraft or Harry Potter (or lord of the rings): https://www.amazon.com/s?k=unofficial+lord+of+the+rings

And maps "in the style" of Tolkien but covering the real world or other properties are likely entirely fine.