But even so, having something in the constitution is of relatively little protection if the judiciary and government are in favour of an idea.
For example, the bill of rights talks about "right of the people to be secure ... against unreasonable searches and seizures" and yet asset forfeiture is still a legal option. Actual practices surrounding plea bargains also look to run counter to the spirit of the BoR, but I mean what do I know.
I don't see how having a bill of rights helps. The only matter of import, and the only protection, is an engaged and motivated voting public. Constitutional amendment might provide a thin layer of protection against short-term rogue actors, but the creeping surveillance state is not rogue by any means, it seems to be a point of international consensus over many decades.
In Australia (unlike the US), constitutional amendments are decided by both a majority vote in both houses of parliament and by referendum where the public votes and a double majority (majority of people in the majority of states, and the majority of people in the country) must vote YES in order for a referendum to pass. And in Australia voting is compulsory so there's no question about election turnout spoiling the result.
So in Australia it is very hard to get a constitutional amendment to pass, and politicians have very little say in whether the amendment will pass (they can block it by voting against it but they cannot force it to pass). Only 8 (out of 44) have passed in the past 117 years that we have been a country.
As for Australia having a bill of rights, I think it would be an improvement (especially if it was anything like the Swiss constitution) but I don't know whether our bill of rights would be ridiculously watered down (not to mention that the US bill of rights is like the 10 commandments -- many people know a couple but don't know all of them and forget that the majority of them are not really relevant today).
If your point is that it's harder to pass an amendment in Australia than the US, based on your description, I would disagree. The US system requires more than a majority vote by representatives, in a couple different ways. The Australian system does sound more democratic.
I would still argue that it is harder to pass amendments in Australia, based on the simple fact that America passed 10 constitutional amendments in the first 2 years of the US Constitution being active (which is more than Australia has passed in 117 years) and that of the 33 amendments that have been proposed 27 of them were accepted (which is a much higher success rate than Australia's 8 passed out of 44 proposed).
So while purely looking at the proportion of YES votes needed and ignoring who is casting the votes, you might be able to argue it could be harder to get something passed in the US because in Australia it requires a super-majority of the public (which is generally a smaller percentage than a majority of 3/4ths of states) which means that it is not purely the role of the government to decide the rules that restrict the government's power. This means that the concern of a constitutional bill of rights in Australia being "pointless" because it would be easy for the government to overturn doesn't make much sense.
It's true that any codified protection of individual rights is worth nothing without people motivated, either in- or extrinsically, to uphold them.
But the power of such shape public opinion, and even people's sense of their, and their country's, identity.
The US, for example, has long had a strain of something akin to "patriotism to the constitution". It's a collective narrative that makes people believe in those rights (and the rule of law). And even those that do not share that believe have historically been motivated to play along, because it was the only way to stay what's called "acceptable company" (or "electability").
Of course we're currently running an experiment if that mechanism still works when 47% of the voting population and half the elected representatives decide to try something else for a change. Currently, it's only parts of the judiciary, and of the media, holding everything up. we'll see how it ends.
For example, the bill of rights talks about "right of the people to be secure ... against unreasonable searches and seizures" and yet asset forfeiture is still a legal option. Actual practices surrounding plea bargains also look to run counter to the spirit of the BoR, but I mean what do I know.
I don't see how having a bill of rights helps. The only matter of import, and the only protection, is an engaged and motivated voting public. Constitutional amendment might provide a thin layer of protection against short-term rogue actors, but the creeping surveillance state is not rogue by any means, it seems to be a point of international consensus over many decades.