This is misleading at best. Is it fair to assume that these individuals are injecting once a week at most and are measuring trough serum levels? Your statement then neglects that peak testosterone is usually going to be 2-3 times the trough level. In such cases a trough total testosterone of 300 ng/dL can easily signify that average testosterone is about 500 ng/dL, which is about the same as a healthy young guy who measures 600-700 ng/dL at his morning peak. The simple solution for the guy on TRT is to split his doses into more frequent injections.
A further confounding factor is that 80 mg TC/week is providing more testosterone than over half of all men would ever make naturally. Therefore it's common to see some suppression of SHBG, which in turn artificially reduces total testosterone, while not affecting free levels.