i just watched Little Fires Everywhere, which is an 8 hour (8 one hour episodes) miniseries adaptation of the book. I loved it. I think this is the modern equivalent of what you all have describe. Thing is, it was so good, they will likely try to get another “season” out of it.
I recall watching a mystery miniseries a few years ago on NBC maybe, but it was average at best.
Network TV likely doesn’t want to invest in mini-series $$$, opting for game shows and reality TV to fill their time slots. Just my thought, I would imagine that something like the North and the South would be expensive to make today, and networks don’t have the view ships the once did.