No one (except Aptera) took Tesla up on the offer to use Tesla’s plug for years because as part of the “open” agreement Musk wanted, the companies would agree not to sue each other for patent infringement. This was obviously a non-starter for most brands; while Tesla was developing some valuable patents around electric vehicles and autonomous driving, the legacy car manufacturers had a lot more patents around everything else related to making a car (and most also had some EV and autonomous driving patents).

The only change really came when the Inflation Recovery Act passed, with a billion dollars earmarked for charging station construction. There were requirements that the stations had to use standardized plugs and allow credit cards (without needing accounts). Suddenly it became more valuable to own the leading Network that everyone could use. Tesla submitted their design to the Society of Automotive Engineers (SAE) for release as a standard and started calling it the North American Charging Standard (NACS). I’ve read there’s been grumbling from some SAE members since the “standard” didn’t come from one of their committees, but as automakers have signed deals with Tesla (that presumably don’t include the old patent restriction) it seems like that ship has sailed. Fortunately NACS and J1772/CCS (the standard from SAE) use the same communication protocol, so the difference is largely electrical/physical.