Batteries are bounded by more predictable chemistry more so than something like the breakdown of a mechanical based trigger waiting for rust or decomposition. Chemistry makes it easier to model and predict. If you’ve got a 1Ah battery and it consumes x watt hours per hour, then it takes y days to burn through. Tolerances that cause the battery to have slightly more or less capacity or component power consumption will likely be <5%, thus not radically different because nobody is timing this to the minute.
True, but even if there’s only one supplier, there’s still demand-side elasticity of price, which means that price increasing causes some customers to not buy the product. Thus, a company may or may not be able to increase a price 1:1 with the tarriff.
All this is fun economic theory, but I was specifically responding to the claim that tax incentives were better than a tarriff. They both translate into some increase in cost of the goods sold.