There is no ASCII representation of a bridge which is actually a bridge. Other engineering disciplines are in the business of producing matter with certain properties; the description of the properties is fundamentally distinct from the matter itself.
There is an ASCII representation of every piece of software which is actually that software: its source code.
This would also explain why "code as spec" goes hand in hand with modern, expressive languages: a sufficiently large C program is not human-readable as a description of its own behavior. If you want to create the program you intend to create, it is necessary to write a specification at a higher level of abstraction, then hand-translate that into C, and attempt to keep the two in sync.
Whereas one can read/write business logic in Ruby, Python, or whatever about as well as they can read/write a description of the same logic in English.