Again, not wrong, but I think the trend is broader. Most maps I've seen of the Americas tend to showcase European cultures. And while in some cases, it may be appropriate to show colonial holdings, it seems to have become a default in the community. This trend is also not limited to the Americas; in many places, when participants get a map of a region they know little about, it's easier to slap some colonies on it than to collect information that advances the original scenario.
I think it's also worth mentioning that actively enforcing the commandments isn't something I typically do, because at the end of the day, I don't want to stifle anyone's creative freedom. Rather, they are suggestions about how to make the game more interesting and to harness TMG's ability to create unique maps and scenarios that haven't been conceived elsewhere.
Any thoughts on changing the Second Commandment? Maybe something more general, such as "Consider how you can showcase cultures that are not dominant in OTL?" Feel free to add your thoughts.