Maintaining my wife's MacbookPro, that never left the house over many years, i've found in the list of preferred WiFi-networks ALL networks, that i was ever connected to worldwide with another Macbook, even a complete new one. Also all networks, we was ever connected to with our iPhones are listed on this Mac.
We don't use a shared iCloud-account. The only thing in common is, that all those devices are connected with the same WiFi at home quiet often.
Although it's not an issue here for me ;), maybe it will be for others getting leaked their locations where they've stored a WLAN-connection that shouldn't be visible to colleagues, partners, children and so on.
My question is: how and why are the networks shared across machines and across accounts/different persons? Isn't it a privacy issue? I don't know if passwords to the networks are also present on her machine, because i don't know how to test it without travelling. If so, she could connect into the networks of several companies i have worked for recently