If I was a developer building 50 new homes, I would want to cut expenses
anywhere possible and install 14 ga. wire/15 amp everywhere unless 12
ga./20 amp was required by code. A few dollars saved times 50 homes can add
up to a big savings and more profit!

If I was a developer building my *own* home, all 120 V outlets and lighting
would be 20 amp with 12 ga. wire.