@Max_S: what’s a “basic right” in your mind?
If it’s equivalent to “those rights enshrined in our constitution that can only be amended by the following difficult process …”, then the flip-flopping of the populace and the party in power isn’t operational. While in power, neither side can muster the political horsepower to change the status quo. Whether that is to add a new basic right or to remove an existing one. They can talk about it as a logical possibility, but they can’t do it as a practical political possibility.
OTOH, if a “basic right” isn’t so basic, and is instead created merely by legislative (or judicial) fiat, then yes, that can flip-flop with the party in power as you say. But ISTM at that point you’re not looking at a truly “basic” right within the definition of your political system. It’s merely a desirable thing, or maybe called a “right” for salesmanship reasons. IOW, there cannot simultaneously be both a “right to life” and a “right to choose”. One or the other of those is not a right.
So in effect, your question turns on these points: Looking forward, how good of a constitution can your society write? Looking backwards, how good of a constitution did your society write?
The US constitution, as was discussed ad nauseum in the thread that spawned this one, has some very good ideas and some rather poor ones. And, after the original Bill of Rights amendment, has only barely been tinkered with, for good or for ill.
Ref the learned @Northern_Piper’s superb post just above yours, many Western democracies have more enlightened constitutions than the USA does. Their constitution writers settled the question of “basic rights” a couple hundred years after the USA did and in a more expansive manner. And their polities seem happy with that settled standard. Largely IMO as a result of having grown up with it.
One of the big challenges all Americans are wrestling with right now is that our system was not designed against the possibility of nihilist vandals at the helm who are supported by a substantial fraction of the political class and the populace.
Our system (checks and balances, impeachment, and all the rest) was designed to stop a small fraction of “bad apples” who were seen as bad apples by the rest of the political class and the populace.
As I said way upthread, trying to alter the rules of the game while the current rules are already being ignored with not only impunity, but to widespread applause, is a sterile academic exercise at best and a foolish direct route to enshrining tyranny at worst.
Witness countless examples in the history of the last ~1000 years, starting perhaps with Cromwell and leading up to current Duterte & Erdogan & perhaps Trump, I don’t believe a democratic system can be built that withstands simultaneous assault by the leadership and the followership.