There's been a successive series of US federal administrations that gave them a pass, either through lack of enforcement or inventing temporary work visas that also covered people who already illegally immigrated: https://en.wikipedia.org/wiki/Temporary_protected_status Biden expanded this authority to cover ~1.2M new people

Also in states like California they let undocumented immigrants get drivers licenses. They can even get bank accounts and mortgages in some states (which is basically impossible here in Canada).