... for a person to be nationally recognized as a venturer, the hat is not required, and belt and grey pants may be purchase from any vendor and be of style appropriate to the needs of the venturer.
Couldn't you be "nationally recognized as a Venturer" just by wearing the uniform shirt? Since the official BSA web page linked by the original poster says that "each crew may determine what, if any, specific uniform pants or shorts they will wear based on crew activities." (It doesn't mention a belt in that section.) So if the crew has decided that they are just going to wear the uniform shirt and everybody can wear whatever pants they want, wouldn't the "uniform" for them just be the shirt, and they would still be "nationally recognized as a Venturer"?
I suppose that a Boy Scout wearing just the uniform shirt also would be "nationally recognized" as a Boy Scout, but they would be recognized as a Boy Scout not wearing a proper uniform, which would not be the case with the Venturer. (Although if you saw 12 Venturers together with the same unit number and 11 were wearing charcoal-grey pants and one was wearing blue jeans, you could make a pretty good guess that that crew had adopted the uniformed pants and that the jeans-wearer was not wearing the proper uniform.)