Technology that works usually gets started right away, planes for instance, 20 years after the Wright brothers they were all over the place. Radio, computers, telephone, trains, this is an example
repeated over and over. See the pattern?

PRT and blimps on the other hand are a bit limited in acceptance and
availability. Shriveled tendrils on the branch of tranport evolution.
DEAD TECH. No hoping for the next "breakthrough" is going to make
PRT work after 40+ years. WVU Morgantown is the goodyear blimp
of PRT. Kind of works, but cost a mint, and does not really work, with limited service and a captive audience.

40+ years is a long time for a tech to "almost" work.