About half of the US doesn't have an economically workable species/breed of tree unless they charge those higher prices. Virgina Pine grows well in the south (was the historical staple crop until 20~25 years ago), but doesn't naturally grow in cone shaped, and requires trimming/shaping and spraying multiple times a year for the 4-8 years it takes to get a marketable tree. Most southern tree farms have replaced V.P. with Leland Cypress (not really a cypress) or a similar/derivative breed of tree with promises of low/no required tending, but they also ended up having pretty high maintenance costs and don't market as well. (They look more like privacy bushes to me, and are also sold for that purpose at nurseries.)

So it ends up being cheaper/more profitable to ship trucks of harvested firs/etc from where they grow almost naturally, and "export" them clear across the country.

Also, the actual/current market for locally grown trees (at least in the south) is sustained 99% by people who still want the experience of choose-and-cut. And that also costs more to run than a commoditized crop.