Errors depend on the scorer, and so are a terrible metric.
Just messing with NatsAddict 
Actually, there is a lot of truth in that. The ball that falls between the SS, 2B, and CF as they stand in a small circle should, by the rules, be an error. However, it has for whatever reason, it has customarily been call a hit. So, to make stats comparable, you follow the custom. Mental miscues show up in the stats as hits. The hitter gets the benefit of the doubt in H/E decisions. The non-assumption of DPs has saved several inept SS and 2B (*cough* Uggla *cough*) errors that a competent SS or 2B would have turned and gotten an assist. It doesn't affect any of the conventional fielding stats such as FPCT or ZR, only showing as a lower DP count and lower number of assists. I'd like to see blown DPs at least be a non-error stat such as WP and PB, and be considered similarly for ERA.
[EDIT: actually, lower number of both errors and assists would affect FPCT unless the FPCT was .000]