The short answer to your questions is that they are driven by party ideology, even if they swear they're not; the Republican ideology controls; and the Republican Party has ceded its own control to Trump (another cult of personality in the Reagan style). Hence no real checks and balances: teamwork makes the dream work, take full advantage of the opportunity.

The government is no longer working on the premise of checks and balances between the branches, but rather on one party overwhelming the other in all branches and in a two-party system — even in the Judicial Branch, despite its contrary protestations.

The Republican Party, now in power in all three branches (and dismantling, impeding, and overriding the "fourth branch" — the administrative state) has demonstrated that it is willing to support a strongman who will ruin the career of anyone who steps out of line (or worse). Few in the nominal party (Liz Cheney, Mitt Romney — largely the old guard) have the courage to stand up against it, regardless of motivation from institutionalism, patriotism, ethics, or personal advancement or greed. The courts should be running on all cylinders now, and some are — only to be stymied by SCOTUS and the Federalist Society crew in the circuit courts.

Even the recent (unanimous) SCOTUS order in the Abrego García case emphasizes that the Judiciary should stay out of foreign affairs and leave that to the Executive — but where the Executive disappears someone to a foreign prison without due process, methinks the emphasized checks and balances should be flowing the other way. The other problem is that the Judiciary depends heavily upon logic and reason to check and balance, with little physical enforcement power — but where the Judiciary itself is politically motivated (I give you, by way of example, Alito's flags and trips; Thomas's house, R.V., and wife; Trump telling Roberts in Congress "Thanks, I won't forget that" [paraphrased]; etc.) and where the Executive and its pet Republican Congress are, shall we say, largely impervious to logic and reason (even from their own hand-picked, Federalist Society jurists) and vocally willing to disregard rulings, where does that leave us?

The system is so deeply rotten that it would take a generation or more to clear out the courts; but for that we need logic and reason in the White House and Congress; for those, we need voters with logic, reason, critical thinking, and the ability to forecast past the noses on their faces; and for those we need good examples, good education, and supportive society. Yet we have a felon in the White House; professional wrestling in the Department of Education, making sure our kindergartners are familiar with "A One"; and the oppression and bilking of the lower and middle classes (I give you the recent and fairly evident insider trading on erratic tariff moves that themselves can only make life worse for those classes as a whole).

It's a vicious cycle: "Against stupidity we are defenseless," and "Against stupidity the gods themselves contend in vain."

The only ways I see to head in the right direction are to keep voting the offenders out; vocally opposing the government's nonsense in multiple fora (even in this one, where comments like this one are often unwelcome); confronting those who support the nonsense with reality; focusing on making our immediate environments better; and encouraging others to do the same.

All things considered, I too have considered heading to the EU. But not everyone has that option, and I like to think that America and Americans aren't so powerless as to fail so ignominiously — that we can right the ship once we collectively wake from the fever dream. Time will tell.