It varies by age -- very rarely see anyone over 30 with long healthy hair.
Bottom line -- it is rare. Even when you see groups of Ethiopian women who typically have gorgeous thick shinny hair, it is rarely MBL or WL. The only people I see regularly with hair past MBL who have hair that remotely resembles AA are Dominicans and I know for a fact that a lot of the things that the stylists do to AA hair (e.g., extreme high heat blow out on relaxed hair!), they don't do to their own. On the other hand, to be fair, Dominican products, detangling techniques and re-introduction of roller sets are probably responsible for a lot of increased length by AA women.
One thing that WL women seem to have in common (other than a lot of roller setting), IMO, is that they are quietly passionate about their hair -- they don't go around preaching and reprimanding, but if you watch and observe the way that they care for their own hair -- it is obvious that it commands a lot of their time, energy and focus.