...; it's rare indeed
for a tuner to be able to match the same range of impedances over its
frequency range. Some tuner topologies even have "holes" in their
coverage.

This is why it is so pointless to specify the resistive SWR range. It is
really only an indication. If your antenna system winds up with an
impossible match at some frequency, you need to try something different
anyway or suffer loss or damage. Hope the autotuner algorithm knows how to
deal with that.

There was a QST test review years ago that compared several popular tuners.
Old and new.