My understanding of Clear is they positively identify me via iris scan, then match it up to a background check and my KTN. With that, I’m a “known traveler” and don’t need an experienced officer to review my documents.
$100 or $189 is trivial compared to all the plane tickets and other expenses of travel. Over a couple dozen trips a year, I’m grateful for the reduction in waiting time and stress.
If there was another tier that had an even faster and more pleasant experience, maybe off to the side somewhere, I’d pay double.