I don't particularly agree with you; I've often thought that amounts to trying to win the debate by nuking the entire playing field. Even if you win, have you?

But I can spot you that anyhow, because there's a perfectly reasonable fallback position: This is illegal. It's a copyright infringement at the very least, and possibly other things as well. And being "illegal", the "what are you gonna do about it" actually has clear, well defined answers. Smartcar.com is doing them a favor by serving a cease & desist, as there is nothing preventing them from moving straight to legal action.

Copying a design is not illegal. Unless the design is patented (which it doesn't seem to be or the OP would likely have said so in the article), everyone is free to copy any design they want.

That you wish something was true doesn't make it so, unfortunately.

What is not OK is copying the documentation verbatim, that is copyrighted. However, that is, frankly, the least of the problems (and easiest to rectify) when someone is taking your product idea wholesale.

I see two issued US patents for smartcar: https://patents.google.com/patent/US9870656B2/ https://patents.google.com/patent/US10169825B2/

Those patents are directed towards "method[s] for processing requests for vehicular data", which at first glance appear unrelated to the descriptions of web APIs authenticated by OAuth that Smartcar is complaining about.

>everyone is free to copy any design they want

Copying text or pictures would be copyright infringement.

So, I'm wrong about this act being illegal, because it's not illegal, except for the parts where it is illegal?

even if its illegal, its nothing unless you win it in court.

I think I mentioned that when I said "moving straight to legal action".