We don't want to spin up wafer fabs because, historically, they had a tendency to turn into Superfund sites. That's why the more modern approach is to build the fab in the middle of a frickin' desert.

Historically, but likely not anymore. You wouldn't be allowed to casually poison the ground in a Western factory anymore and we have the technology to keep the environment mostly clean. I don't even see it being very expensive compared to other fab costs. Have a sealed floor and proper waste / exhaust processing, don't spill in the first place. Things must be extremely well controlled anyway.