... The State could come in and say if ev powered you could go 82,000 lbs.
With less vibration ,more even distributed power to the road and a safer truck, everybody would win including better road conditions.
I doubt engine vibration has any relevance to load limits; I don't think regulators even care whether an axle is driven or not.
More even power distribution? I don't think so: conventional trucks use simple differentials in each axle so both drive wheels get the same drive torque; the two axles are connected directly so they run at the same speed regardless of traction. While individual motors per wheel (or dual wheel set) are a good thing, there's nothing about the conventional setup which hurts the road. I find it interesting that Tesla chose not to power the front axle, a configuration which is problematic with a engine but would be easy (but not so cheap) in a battery-electric vehicle.
I don't think there's a precedent for allowing higher (and thus more destructive to the road) axle loads as a reward for a safer vehicle. For instance, ABS doesn't earn a higher limit, as far as I know.
With more axles, total combination weight can be increased without exceeding the allowed axle weight, and this is already considered by the various limits allowed for various truck and trailer configurations. Perhaps some heavier combinations could be allowed with stability control, but individual control of drive wheels on the tractor is unlikely to be enough to be significant to the stability of multi-trailer trains. When there are 9 axles on a rig and one is steering, improved control of two of them probably isn't as important as control of the other six.
Volume is not the issue, look space under the trailer
I would agree, except that the trailer is not the truck. Even if high-voltage high-current wiring connections were acceptable between them, the tractor (truck) and trailer are often not even the property of the same owner. Only select specific operations could tolerate having to use expensive specialized trailers to make the tractor workable.
Of course there are also trailers which do not have space under the deck which is suitable for a battery pack - primarily some types of bulk carriers, and the lowest of lowboy equipment carriers.