Most of the good machinist knowledge in America has retired, if not already literally died.
And mechanical engineers in the US largely don’t have the hands on skill to really understand making these machines. Not that that can’t gain it.
But to achieve truly high precision (the pinnacle from which all other percussion is derived) is an extreme art form. CNC doesn’t come close. The state of the art (and has been for eons) is hand scraping: https://www.krcmachinetoolsolutions.com/machine-tool-scrapin...
Things used to be made better because people cared about making a good product and took pride in their work. This is especially true in the machine tool industry: don’t try to make it in the field if you don’t really legitimately care.