Two good reasons. 1. There are some issues with heavy vehicles. They put more wear on the roads, they pose a greater risk to other drivers because of their hig

Two good reasons. 1. There are some issues with heavy vehicles. They put more wear on the roads, they pose a greater risk to other drivers because of their higher potential energy in crashes, and they consume more energy (e.g. power plants have to burn more coal). 2. Current EV battery technology uses resources that have significant environmental impact. Smaller battery does less damage. The goal of this proposed battery weight tax seems to be tweaking the trajectory of EV development towards an even bigger environmental win.