A MacBook computer was stolen from a friend. How would one go about finding it? It contains unprotected passwords and was used mainly for email. No banking or finances were on it. I know whenever I'd go to the library in an outlying town, and use their computers, my Google mail would notify me that my account was accessed on such and such day and it was a Mac computer or Windows system that was consistent with the system that library uses.
If the thief, or the person it was sold to, were to access the internet, because every computer has its own ID, would it be possible to locate it that way, or does that only apply to Edward Snowden's stolen computer?
Police are not in the 'find-and-return stolen property' business, but it would seem to me that a non-invasive (i.e. no search warrant required) check of the prime suspect's server address would show the computer IDs of all computers logged into that IP address.
Could the rightful owner of this computer utilize email providers to track the location of where the stolen computer was used?
If all the Mac numbers from the original purchase receipt were available, that would have to be helpful, no?

Unless she has it registered with Apple..(which could lock and wipe it remotely). or some other third party program (ESET offers this as part of their package for example) when it MIGHT be tracked by location when its in use, then she isn't getting it back. All provider records would require a seperate court order, on a provider by provider basis. Real life isn't like CSI or the Movies.

Issues of National security also are completely different than petty theft.

It is true that every computer has a unique hardware ID called a MAC address. However it is not that easy to search and determine when a particular MAC address is used. Google will identify the type of computer based on general info stored on the computer. More specific info more from cookies.

I'm not sure what you are referring to as the suspect's server address. Each computer that connects to the Net is assigned an IP address. The only entity that can tell who was assigned that IP is the ISP that person used to connect to the Net. And that requires a court order.

First go and change every password for every account and not allow them to use those.

No, unless you have a location program in it, it would not be able to be found