>>1511851Well at out shop we actually machine a lot of one off bike parts and do our own anodizing in house.
Short answer is its actually hard to constantly do parts the size and complexity of a frame, and if its not absolutely perfect you have just binned an other wise good frame.
I have often thought the same, i love anodizing but painting just makes more economical sense. Also FYI some alu frames have a hard anodized primer beneath the paint.