Knowing what people employed in similar roles to you earn helps you bargain for an equivalent salary

In theory, not sure this translates to reality. I don't even have anecdotal evidence that this works. Employed in similar roles does not mean equally valuable to company. I live in Norway and I don't think I would ever tell my employer they need to pay me the same as someone else, I also know there is significant variability for pay in the same role at places I worked (without ever checking public tax records).

Kidnappers no longer need to waste time scoping out potential targets.

Traffic fines in Finland are proportional to the offender's income.

https://www.irishtimes.com/news/nokia-boss-gets-116-000-spee...

Simple, elegant and fair?

Mathematically perhaps, but people are people...

https://www.automotive-fleet.com/10481/nokia-executive-fined...

> Traffic fines in Finland are proportional to the offender's income.

Don't need everyone's income to be public information to do that.

> Don't need everyone's income to be public information to do that.

It depends if you want speeding fines to be transparent, or secret.