I think they need to be citizens to be protected by the Constitution.
Due process, probable cause, habeas corpus
Because the state was not supportive in this endeavour.
In Canada and Australia federal and provincial governments tend to coordinate and especially in Canada, a centralized national government is strong.
Well, if the state won't cooperate
America has a system often called dual federalism (vs centralized federalism of Canada and cooperative federalism of Australia). In the U.S. federal and state governments operate in different spheres and may openly resist each other. (See history of Civil War.). In the U.S. it is constitutionally normal for states to refuse to enforce federal programs, pass laws directly challenging federal priorities, and frequently litigate against federal government. This is very different and probably feels “wrong/abnormal” to Canadian or Australian political culture.
A key difference is that in U.S. the president is not elected by congress, there is no parliamentary system. The executive is separate from the legislative and does not depend on a parliament for approval to change or enforce immigration policy, the way prime ministers and the cabinet would in Canada and Australia.
State resistance is NORMAL. States can refuse cooperation, sue the federal government, and pass laws directly challenging federal policy. This creates ongoing visible conflict. CONFLICT IS BUILT INTO THE STRUCTURE.
In Australia and Canada immigration policy comes from parliament so the prime minister is responsible for enforcing it. Provinces negotiate with the federal government but rarely engage in regular constitutional standoffs. The political system discourages open executive vs provincial combat.
From a Canadian or Australian perspective you might ask, “If immigration law exists why wouldn’t it just be uniformly enforced?” In your system if the federal government wants enforcement, it generally gets enforcement.
In the U.S. enforcement can swing drastically between presidents, states can refuse cooperation, and courts intervene constantly.
So what you deem “chaos manufactured by the left” is constitutional friction that is built in to the system, state-level autonomy, and a very strong tradition of American protest politics (see January 6th example) misread as coordinated destabilization.
From inside the U.S. we call it polarization. From outside you see it as systemic breakdown.