I think the 'Pro' part of the name is a good indicator that this is a business-to-business venture, not something aimed at consumers. In that respect, 6 cents per image seems quite reasonable. If you're generating images for a business, paying a human to even visually review image quality at 6c per image is basically sweatshop wage.
If you're generating images for personal use, there are lots of open weight models that are quite capable.
Not really because you're paying for the roll of the dice not to get the actual desired image. So it's more like the minimum it would cost is 6c with no celling.
Of course it is, but it's not an either-or expense it's both-and. For most projects you need to do a lot of trial and error to get the right image, so it's the cost of someone who knows how to do that trial and error effectively + probably a few hundred generations per hour.
If you're generating images for personal use, there are lots of open weight models that are quite capable.