It's not that they can't, but why would they? It's a race to the bottom commodity wise, much smarter to build on top of the model layer like Legora and Lovable than make the models.
How many times will we do this? This line of thought is precisely why we can't build almost anything, and China can built almost everything. We could do X, but we're too smart - let's offload the actual work to China and we'll run our economy on IP and B2B deals.
... Built using expertise, machinery, and/or factories from Taiwan, the Netherlands, and South Korea.
The supply chain is far more complex and globalized than you're trying to make out here.