From my extremely naive understanding, obtaining credit and low rates is, in general, much easier in the US than other places. So it makes sense to me that it has “artificial” tools to help determine risk. How do other countries handle this and provide the availability that can be found in the US?
From what I've seen, most developed countries actually do have the equivalent of the US credit reporting agencies. It's just that the functionality goes by different names and is distributed across several different types of entities rather than being centralized in three credit reporting agencies (plus Fair Isaac Corporation / FICO which is a vendor to all of them).
For better or worse, it's not really possible to have a modern economy with high growth rates unless lenders have a reasonably reliable way of quantifying borrower propensity to pay. Debt to income ratio is a piece of that, but some people are just deadbeats.
In my experience, rates are not low in the U.S. They are high because high risk loans are able to be granted.
The availability of debt for things like housing and cars is very complicated, but high taxes, a high degree of education, livable minimum wages, and realistic employee rights helps increase stability and decrease risk. I don't say it to be flippant. It is more complex than even I understand. It's only to say that, given that these systems are designed artificial systems, there are multiple implementations that work under various constraints and incentives.
For bankruptcies and defaults, there are similarly court records from public institutions, which you give a bank access to. They cannot search these sources without your consent, though of course they will then not loan to you.
This is the aim of every culture & political system: to remove the ability to even consider that other ways of doing things are possible and that other countries doing things differently are terribly flawed compared to the paradise you live in.
In Scandinavian countries there are registries of your income (from the tax authority), your debts (including buy now pay later which are technically flexible loans) and any bad debts you have that have gone to debt collection. No history of previous balances, repayments, how long you've had a credit card, etc... Companies use this to come up with a score, either themselves or a company like Bisnode will do it for them. So basically it's a simpler calculation based mainly on current situation than history.