[riku_iki]

They have employment based green cards (not through marriage), it requires labor certifications with advertisement and checking local candidates: https://www.dol.gov/agencies/eta/foreign-labor/programs/perm...

[LorenPechtel]

You get the green card *after* a certain amount of time working. The years in the job is the qualification to apply.

[riku_iki]

this is not true. I think green card application can be submitted and approved even before work started (though this probably very rarely happens), employer just need to go through certification process(prove that job requires education and skills) and prove that there is no local competition for the job.