Hmmm yes, they can go for a walk in a park. But they can’t use TANF, Medicaid, SSI/SSDI, SNAP, or anything else that requires means testing. While they do get taxes withheld from their paycheck. So they are actually paying for that park.
Yes some are on a cash only, under the table arrangement. But 100 billion dollars worth of them are not. Banks don’t require proof of citizenship, and states that aren’t busy trying to shoot themselves in the foot aren’t checking citizenship for work. So they get taxes, the immigrants get worker protections, and life goes on as normal.