Maybe this is a dumb question but why does it require a 50k$ spectrum analyzer to see the returned signal from the tag? The frequencies involved aren't that hi

Maybe this is a dumb question but why does it require a 50k$ spectrum analyzer to see the returned signal from the tag? The frequencies involved aren't that high (<1 GHz) and I don't get the impression that the symbol rate is particularly high. Is it below the noise floor for low cost SAs or something?