Good point, if you use vouchers as the gold standard of species distribution, you can’t be surprised if vouchers continue to show the same distribution patterns. To be honest i suspect the truth is somewhere in between. Vouchers focus on conserved land and known biodiversity hotspots, whereas ‘private’ land, areas which receive little scientific attention, and urban areas will be underrepresented in the vouchers. You can’t really say much about distributions and populations without systematic (like a grid) or randomized sampling. Sometimes that occurs but it doesn’t seem to be what comprises the majority of vouchers.