Also a bit remarkable is that your social security number (personnummer) is not only used to identify you with official and government services, but also with every company you might have a customer account with. It consists of your birthdate and 4 numbers (which some people use as their pin code on their devices).
On the other hand there's 2FA: when identifying to a service (like when calling customer support) you're asked for your personnummer, after which you have to open an app on your smartphone to verify with a 6 digit pin code.
The trust in eachother went pretty far apparently, where garage sales sometimes just meant an open barn with a notice. Things for sale would have the price + an account number to make the payment to. (But haven't come across this myself yet, times are changing)