> If you pay someone to paint a picture, who owns the copyright?
that depends on the terms of the deal. Some artists want to keep the copyright but will sell the work, while others are happy to sign their rights away for money.
> If you pay for an AI to paint a picture according to your specifications?
Copyrights are for humans, so if you pay an AI, because the AI isn't a human, it never had a copyright to sell you. You paid for an image without a copyright.
Copyrights are owned by corporations as a result of either:
(1) actual human authorship and original ownership, sold to a corporation, or
(2) actual human authorship as a work for hire on behalf of the corporation, which is a special case specifically laid out in copyright law which allows someone other than the person performing the actual act of authorship to be the original copyright owner.
that depends on the terms of the deal. Some artists want to keep the copyright but will sell the work, while others are happy to sign their rights away for money.
> If you pay for an AI to paint a picture according to your specifications?
Copyrights are for humans, so if you pay an AI, because the AI isn't a human, it never had a copyright to sell you. You paid for an image without a copyright.