That has been said about this too. The international energy interests have too much at stake to let it get out. That may be why Toyota went public with it and even explained the technology so it can't be easily contained.
"Toyota has developed a hydrogen fuel cell that can separate hydrogen within the vehicles; this hydrogen then reacts with the oxygen from the air and produces electricity. This generated electricity is used to power the electric motors, driving the car’s wheels." https://unreadwhy.com/end-of-evs-toyota-to-make-car-run-on-water/
It took a while to get to the link @Ed Wilson but when the text started, it said that Toyota didn't rush into EV development as other car makers did. In fact, I think Toyota had the first mass market EV, the Prius. Toyota brains saw that there was no long-term future for EVs due to the reliance on batteries and the associated impact on the environment of disposing of those batteries and even of the production of them. They (Toyota) first developed a hydrogen fuel cell powered car a few years ago, but the was really applicable to fleet use, at least in the U.S. Using outside power to drive electrolysis, which then powers the vehicle has been thought to be the solution for Toyota. Only the passage of time will determine who was right.