> Citizens would have to put up with some pretty draconian living conditions to ensure zero illegal migration.

I don’t agree. It’s a matter of incentives. If you know entering the US illegally means you stand a high chance of being deported, have almost no ability to be employed and no access to any social services, the problem mostly solves itself.

Lots of other countries ask why the US has problems other countries have already solved and immigration is a great example of it. It’s a solved problem, our leaders intentionally don’t want it fixed.

> Even Reagan granted mass amnesty in the face of such costs.

The amnesty was an agreement that substantial legislation would be passed later than would stop illegal immigration. That’s why Reagan agreed to it. But the changes never happened.

> But significant change probably requires replacing the Fourth Amendment

The Fourth Amendment can stay as is. Just stop people from staying illegally in the country and the 4th amendment becomes a non-issue.