One really goofy part is you don't have to prove as an employer that you can't find a domestic worker to apply for an H1-B. You do have to "prove" you can't find a domestic worker to convert an H1-B to a green card.

Like, under the law technically you have to fire your H1-B worker and replace him with a citizen, and only if you can't find a citizen can you convert him to green card.

This is kinda bonkers and leads to all the fake job postings with weirdly specific requirements. They basically take their worker who has already probably been working at the company for 6 years and copy-and-paste his resume in the job description, then fake advertise the role, to "prove" they can't find anyone, because if they do find someone that means they have to fire the person instead of getting him a green card.

It makes far more sense to make a company prove they can't hire a citizen before allowing them to hire a foreign worker, rather than allowing them to hire but then making them go through a kabuki theater fake recruiting process to convert the person's status.