> Illegal immigration hasn’t shown any real harm to people that regular citizens don’t also take part in

Eliminating competition comes with the territory of survival.

> you can’t have a country of rights if you don’t extend those rights to non-citizens within your borders.

Sophistry. "Rights" asserted by contractual violation are invalid. If you pirate Windows you don't get to sue Microsoft when WGA denies you access. Expectation otherwise is an assertion of dominance by the weaker party.

You don't have a country at all if you don't enforce borders, which become meaningless in practice once you extend ingroup rights to outgroups. But you know this, hence your phrasing.