They did this a few years back. The only way to increase efficiency is to super insulate the heater. They did this and the price of an electric hot water heater jumped from $200 to $400. But there is an even bigger issue. The heaters became larger. And they often no longer fit in the spaces that were designed for them. And the spaces can’t always be resigned as there might not be any room to do so.
The difference in putting more insulation in them is going to be extremely minuscule as they are already close to the max. And the price will jump even more.
These authorities just love to come up with ways to push their authority. They are really causing pain out in the real world. Soon many people will have to go without hot water.
So true. Mine almost didn't fit. (see my #21)