Good observation. Meaningful field work with any likelihood of success is hard work. Boots on the ground several days a week over months of time. Without that investment in time and sweat equity, even in a BF active area, chances of contact is unlikely. The BF prime directive seems to be avoidance of humans and unless they make a rare mistake, human contact will not happen. They are very good at avoiding us. One exception to that might be if one of their older juveniles, gets to know you and decides to mess with you. I think even that is discouraged in their culture or else adults would continue the practice into adulthood.
To support that, In my case, I found an active area because of past activity, but it was 4 months of being in the field at least 3 days a week before I found my first footprint,.. That footprint lasted only about 20 minutes before it was obliterated by 4 human hikers passing through. I was very lucky to find it at all.