TastyBrew does give ranges:
Wheat Beer - Bavarian Weizen (3.6-4.48)
Wheat Beer - Bavarian Dunkelweizen (3.6-4.48)
Wheat Beer - Berliner Weisse (3.45)
Wheat Beer - Weizenbock (3.71-4.74)
I was a bit afraid the last Paulaner clone I brewed, as I went for the higher end of this range; it came out most excellent. The BJCP style guide does not provide any numbers, only guidelines on "mouthfeel" which of course includes other variables. I think much of this is a matter of taste, within a given range for a given style. One reference I found stated: Most North American commercial beers are carbonated to 2.5-2.9 volumes. British cask ales are between 1.5 and 1.8 volumes (this 100% difference in carbonation is the reason why a lot of North Americans think the British drink their beer 'flat'), while some German Weizen beers have 3.0-3.5 volumes.
This is an interesting topic for sure; and I do not know what either BeerSmith or TastyBrew base their numbers on; but Palmer's book on page 113 shows volumes of CO2 by style that are consistent with that of TastyBrew (Germany Wheat 3.3 - 4.5).