Modern states are to a large part insurance providers. Citizens pay premiums and get health care, pensions, disability care etc. Insurance works when a large g

Modern states are to a large part insurance providers. Citizens pay premiums and get health care, pensions, disability care etc. Insurance works when a large group of people pay premiums to protect against some condition that has not happened yet. If you could sign up for a fire insurance once your house is burning, the system would collapse. For similar reasons, modern states need to keep poor people out since, on average, they will be a large net burden on their welfare systems.