My observation is that pace of play is the product of the culture and expectations of the core of regular players at a given course.
Some courses, mainly private, have a culture and expectation of fast play, and fast play results. Other courses, most of which are public, have a slow play culture, or expectation, on the part of regular players, resulting in slow play.
My observation is that the course management and staff plays the major role in establishing the pace of play culture. They can inform players as to the expectation of faster play and explain what will be done to encourage it (for example: marshals giving friendly warnings and having the authority to ask players to pick up and move to the next tee). By simple communications that set expectations, backed up with good marshaling practice, the culture can be changed over time. Every player should be informed and reminded before teeing off, and perhaps given feedback at the turn..
I play two nearly identical municipal courses, five miles apart. Same design with green-to-tee walks minimal, same difficulty & lost ball hazards, same conditioning.
One course clearly states pace of play expectations and has marshals warn people (and very rarely move a group). It's not uncommon to get told by the starter at the turn that "nice job - you played that 9 in 1:45", or "2 hours for 9 is pretty slow". the course plays in less than 4 hours on weekends. Regular players expect that and remind each other. Tee sheets fill up.
The second course does no communication on pace of play and has marshals that sit in the shade or look for golf balls. Play there always takes 5 hours or more. When asked, the pro has replied "Nothing we can do. We hope for 4:30, but someone is always slow." Regulars accept that pace & never hurry as they know they will wait on the next shot. It’s easy to get a tee time there.