You remember me, right?
Why haven't you called?
Dave, you're discussing the question we've been asking for 40 years. . . Nobody has any answers, but there have been some "tricks" that have snared a few back into the water.
When asked questions new divers think we're the Scuba Police. . . so they won't give an answer. When a "friend of a friend" answers. . . it seems embarrassment that your student didn't "instantly download all your knowledge. They may have expected to become "Masters" of all that could be known underwater.
New divers expectations may be at fault. . . Are they coming out of a certification class expecting to be great divers? Is their ego unwilling to accept a beginning explorer role? Does the presence of experienced divers drive them away? The same questions year after year, after year. . .
I have no answers, but a few experiences, that have some success. . . At local dive site, I'll approach younger divers while I wear shorts and a tee shirt "mysterious stranger" I'll ask how they find "todays" conditions, and offer another location that is "usually better". The underwater park is crowded and muddy. . . That shoreline over there is empty, but a very good dive site.
If the new diver comes to the lake with a boat. . . There's a dive shop that gives out "boat diving maps" that I created to let divers find entry level sites. Someone dives our lake in the spring an labels the lake a mud hole. . . I point out the visible creeks that are running brown, and show the upstream shore is still clear.
Please help, I've tried many ways to drag the new divers into the lake, but they need some "innocent" pull to find a prize they can bring back to their instructor. Add your ideas, I can always adapt your good ideas to our lake, and our reluctant new divers.