What does it mean for a technology to follow Wright's Law?

> Most technologies do not follow Wright’s Law – the prices of bicycles, fridges, or coal power plants do not decline exponentially as we produce more of them.

I would bet Roser is wrong here and he can't provide a reference for his claims here. I'd predict that they do decline exponentially, it is just that (1) we have already produced a huge number of them so it's hard to observe the next doubling of cumulative production, and (2) the learning rate exponent is a lot worse than in the more obvious examples like solar panels or deep learning.