> how about just keeping a log of loans and payments

Why does my landlord need to know how much my student payments were ten years ago? Or what sort of car I drove then, and how long it took me to pay it off? Or that I once owed money to deplorable-sex-dungeon.com, or whatever other arbitrary thing they find offensive?

As someone who is always on the receiving side of this nonsense (I have no credit, never take on any debt and have always paid my bills), I'm completely with you.

if I were* a creditor, I'd find it pretty valuable to know if a prospective lender was a deadbeat. just trying to find a middle ground here. my score is awful because I never borrow any money. i think that should be qualitatively different to a potential creditor than someone who doesn't pay their bills.

for some number of years that meant traveling (car rentals, hotels) was a huge effort. getting leases on apartments was easier because of references. a mortgage was possible in the seedy 2000s, but not any longer.

A landlord is taking a tremendous risk by letting you rent.

Things renters can and will do include not pay rent, incurring several months (or worse) while being evicted, trashing the house.. if they behave badly or just can't quite keep up with timely payments and you have to rollover to a new renter that is pretty expensive, too.

This isn't to say credit scores are perfect, but they are so effective a predictor of conscientiousness, insurance companies rely on them to predict someone's likelihood of a car accident - on average, they work.

I'm not arguing against credit scores, I'm arguing against my landlord being able to see a detailed history of my non-cash purchases.

They wouldn’t see your credit card transactions; They’d see your credit card payment history. Big difference.

Those are all instances that can be abstracted behind random account names: Account 1,2,3,4,5. And amounts as simply "payments" into an ongoing credit account.

Sure, could I deduce that $1200 a month is for your rent? And that $250 is your student debt repayment because you've been paying it for 10 years?

Anywho, there are different ways to present your credibility as a debt repayor without leaking too much. Not that I'd mind giving out detailed information, as long as they ask my permission first.

That landlord is allowing you to move into her property and if you decide not to pay your bills (or to airBnB the place out for drug parties) said landlord will be out of pocket somewhere around 6 months of rent (eviction takes a long time) plus legal fees and repairs.

Because it's a good proxy for knowing whether you will make your lease payments

This is actually how it works. The lender gets to pick the scoring model they want to used based on the raw data provided by the credit bureaus. The credit scores you see on e.g. creditkarma are just one of the many models in use; they're all pretty similar in practice, but vary by a few points depending on what they emphasize.

Is that why when I was applying for financing while leasing a car, my score was a bit lower than what Credit Karma was showing me?

Yes, different algorithms. Credit Karma shows you VantageScore 3 and car lenders usually use FICO 8.

Credit Karma is always about 20-40 points higher than your real score, in my experience.

They aggregate "events" reported by various creditors. Miss a utility bill and it goes to the centralized databases. That's why you so often need to provide SSN to activate services with post-paid debts.