Yes they do, but not in the great numbers that they used to.
Nowadays so many of them have vehicles of their own, or if not, a close friend or relative has one.
When my wife was a student nurse in the early '80s she bought a Honda Cub - à crédit - and only very rarely used songtaews after that.
They will go the way of the samlor sooner rather than later... mostly for tourists.