Lower prices don’t often fix a product strategy problem. Tesla just reported first-quarter deliveries of about 358,000 vehicles. Way below expectations, again. Production continues to outpace sales by a wide margin. And growth, routinely projected at 50% annually, has slowed to low single digits. What’s going on here? It’s probably not a pricing issue. Tesla’s already introduced cheaper versions of the Model 3 and Model Y. And guess what? It didn’t move the needle. Which points to other...