Because of force of habit. I work for a NFP with membership of China and Taiwan, and we have to steer a narrow course around calling places countries or economies. I got used to this habit.
Somehow journalists make headlines when this happens. Lots of people enter on a tourism visa and do not earn income but are in the us for a mixture of reasons -what gets reported, is journalists being caught and expelled.
I have an APEC card. I only ever enter for work. I think it's considered ok to recreate, having entered for work related reasons.