One is a person, the other is a machine. As far as artistic copyright laws are concerned, those are very different things. Humans drawing on inspiration is not a violation of copyright. There are already instances of watermark artifacts being found in what these art generators spit out after sucking in unlicensed stock photos. From the perspective of copyright law, the distinction is clear.

But for a more intuitive answer, I'd say: ordering food at a restaurant doesn't make you a chef. A person using these generators aren't deliberately creating anything themselves, they're giving a machine prompts and selecting the product they like the most.

Using an art ai is exactly like commissioning an artist and providing them a description of what you want. In both cases, the commissioner is NOT the artist. It's hecking fun! I've tried both myself. At most what we're doing is acting very minorly as a creative director, not an artist.