Sure thing, here you go: https://superuser.com/questions/1005235/wi-fi-opt-out-microsoft-google

EDIT: So looked around some more and everyone points to that link as the main source for this information. That link lists a page on microsoft.com that no longer works. The internet archive has a snapshot from 2017 which states the following:

How we help keep your data safe

Protecting your home or business network

If you manage an open Wi-Fi network at home or at a small business but don’t want Windows to automatically connect people to it, you can opt your network out by including _optout somewhere in the Wi-Fi network name (also called the SSID). For example, “mynetwork_optout” or “my_optout_network”. When you do this, Windows won’t automatically connect people to your open network. For more detailed info, see the section To prevent other Windows 10 customers from automatically connecting to an open Wi-Fi network you manage.

So it sounds like that only applies to open wifi access points and Windows machines automatically connecting to them. Perhaps _optout doesn’t actually matter if you’re using wifi encryption (which you should be). Interesting… I’d like to know where I got the idea that it included bing maps cars…

Thanks for bringing to my attention that I might have accidentally spread misinformation.