At the beginning of the pandemic all the mills cut production anticipating economic collapse that didn’t come. Prices spiked on high demand and low production.

Mills did ramp back up, but it’s unclear to me if they used it as a chance to do so slowly/preserve margins. Lumber never got close to pre-pandemic levels.

Tariffs probably also play a role here. About a quarter of US lumber comes from Canada, and barbed wire is just steel with a little bit of processing.

For products with little value add there’s not anywhere for the tax to be absorbed, and no real way for domestic producers to quickly scale up, even if they wanted to.