It's a confusing labeling problem -- the ticks aren't actually the variables on the plot for the histogram but for the scatter plots -- the axes values are for the scatter plot in the upper right quadrant which is scatter(x(:,2),x(:,1)) while the lower left is scatter(x(:,1),x(:,2)).
So, the x-axes limits are for var2 which are bounded at -1; the labels have nothing to do with the histograms; only the scatter plots. TMW just placed the x-axis labels for all the suplots at the bottom instead of keeping them with their respective suplot locations.
If create a poor-man's copy...
so, while perhaps confusing, looks like the data are in fact correct...I don't have the Econometrics TB so can't go in and query what the actual limits are on each subplot() but doing so will make things clear, I expect. I fiddled around to roughly approximate the appearance on the LRH one...that took some doing...what the logic is that created the actual limits would be interesting to go look at, perhaps.