Worse than vets is hospital system and medical offices. In our area there are about 6 hospitals within reasonable driving distance. 1 is a mayo and the 5 others are split between the two major mega-providers. One of those also partnered with CVS/Aetna to provide marketplace insurance, until they decided that didn’t have high enough margins so they dropped 100k (28%) subscribers.
The healthcare system is just rent-seeking upon rent-seeking. PBMs are another big one where the PBM gets to decide after the fact what your rebate is. No conflict of interest there when United Healthcare owns Optum, which I think is the biggest PBM.