> Companies exist that buy cars just to tear them down and publish reports on what they find.

What does it mean to tear down software, exactly? Are you thinking of something like decompilation?

You can do that, but you're probably not going to learn all that much, and you still can't use it in any meaningful sense as you never bought it in the first place. You only licensed use of it as a consumer (and now that it is subscription-only, maybe not even that). If you have to rebuild the whole thing yourself anyway, what have you really gained? Its not exactly a secret how the technology works, only costly to build.

> Except that they could just buy one themselves.

That is unlikely, unless you mean buying Tesla outright? Getting a license to use it as a manufacturer is much more realistic, but still a license.