To protect the entrenched interests. Who also happen to "own" the politicians.
They use terms like "prevent market disruption", and "allow time for evolutionary change", etc.
But the bottom line is that people who profit from existing products and markets want to protect their markets and their cash flow.
How will they stop Joule from distributing diesel-making kits, consisting of a 55-gallon drum, a processing and collection system, and a starter culture of their little wonder-germs? Suddenly, anyone with their own property can just never go to a filling station, and it’s nobody else’s business why.