On Android you do by granting rights to access your contacts and give full network permissions. So you never know what a program will do with your contacts and a network connection.

Thank you, that was exactly my first thought.

In general, since we all are represented in other peoples' contact lists, it's worth considering what those other people are going to do with our data.

And it's not just the people you correspond with directly. I have a lot of people in my Thunderbird and email provider lists who I have no idea who they are, because someone in a chain of someones sent out a broadcast email with their address and my address.

Which means that if I were the sort of person to "upload my contacts!" I would have exposed people two or more hops away from me to whatever "service" I'd just submitted to.

Uploading your contacts may become the net equivalent of farting in public; it's rude.