Are income levels not deserving of privacy?
"Of course" makes it sound like it is obviously / objectively true, but it is a sentiment that is not necessarily true, either in the past, or even in the present everywhere on the planet.
> your address, phone number, income, etc should all be private just because the phone companies shared this didn't mean it's a good idea
This information was public in the past before the phone companies existed. May I introduce you to the concept of city directories:
> A city directory is a listing of residents, streets, businesses, organizations or institutions, giving their location in a city. It may be arranged alphabetically or geographically or in other ways.
* https://en.wikipedia.org/wiki/City_directory
> City Directories were created for salesmen, merchants, and other interested in contacting residents of an area. They are arranged alphabetically giving lists of names and addresses. These often list the adult residents of a city or area.
* https://www.familysearch.org/en/wiki/City_Directories
They can date back to (at least) the 1800s and continued into the twentieth century:
> City directories were published yearly. The Archives has them from 1834 to 2001 (except for a few years in the 1830s, 1840s, and 1850s, and in 1987, when they were not published).
* https://www.toronto.ca/city-government/accountability-operat...
Even your sense that you should hide it is in service of this and the effort to get people tearing each other down is also just a good way to depress salaries.
... No? I don't think so, anyway. Maybe if people understood how obscenely unequal our society is, it would go part of the way toward fixing that.