Do we know that the stem mounted TPMS doesn't track in a timely fashion, or are we just going by speculation? It would be interesting to see the difference between the two types on the same tire. I would be willing to bet the difference would be much less than one would think.
Truckers are not going to use valve stem TPMS probably because the adding/checking air takes more hassle with a stem mounted TPMS. A stem mounted TPMS adds extra steps. A wheel mounted TPMS is pretty much set it and forget it.