Could you share a similar library you've built without any work?
No but I can point to hundreds on HN.
Please provide a couple, I am genuinely interested.
Do most people need 20k images, or just a handful?
Uh, yes?
What work?
QA and organization of the assets...
The entire point of AI is that it doesn't require work, you just type a prompt in and it does the work for you
Prompting is still work; it requires thought and oftentimes iteration.
It requires time, not work
It only doesn't require work if you want a one-off amusement. If you want something specific that matches the surrounding graphics and shows exactly what you want, you're going to spend time and effort speccing it and iterating.