Nope, didn't misunderstand this either:
You seem to be confused about fact; don't worry it's fairly common here. An amendment doesn't confer legality, ultimately the SCOTUS confers legality and that boat left the shipyard 70 years ago, has come in for refitment a couple of times, and delivered a few million passengers all while being an incredibly bad design from the beginning.
So as far as your codified entitlement:
Section 7. No person shall receive compensation from the United States for any reason except labor, payments to injured veterans, earned pensions to employees, and as payments made for prior social security taxes.
Congratulations, you've just codified a budget busting entitlement that preferences the old over the young to boot. Perhaps we shouldn't use the Constitution for legislative purposes unless you think Prohibition went fairly well.
Why are you proposing a Federal amendment that forces the States to act in a particular manner? indeed.