So far, yes they have been. But Tesla is starting to put storage at superchargers a bit more often now. There are at least 3 or 4 recent ones that have or will have a megapack battery with them. So far we've only seen them doing it in CA though. The problem for Tesla is that their calculus on whether adding storage to a site is financially worth it or not is more complicated than EA's. Tesla has to consider the cost/benefit of self consuming batteries vs. selling them to other buyers or using the cells (or cell production capacity) in the vehicle division, etc. If they had a lot of excess battery production capability, this wouldn't be an issue. But as they don't, this is much less straightforward than doing a relatively simple calculation on expected savings and ROI.
