My examples anchored it to avoid matching outside of the expected field. That probably wouldn't matter for the easy data used in the csvkit example but, for example, suppose you were looking at business data and your search for California included records from every state with a California Pizza Kitchen, California Tortilla, etc. Or, the reverse, you want your search for Washington to include records from the state but not DC.

This class of error is somewhat treacherous since it's common for people not to notice it before they start working with a full data file. Using tools which don't require constant caution to avoid data errors is simply a basic good habit.