The difference is- the producers of shows such as Mister Rogers and Sesame Street did not have a profit motive to increase "engagement" numbers. They actually used psychology to try and improve the outcomes of their viewers (aka children) rather than trying to improve the outcomes of themselves.

I mean, watch CoComelon and Sesame Street (or Mister Rogers, or Daniel Tiger...) side by side and tell me there isn't a qualitative difference between the two.