I think part of it is that contracts are mostly interpreted by trained humans. A computer works through each line of code before continuing to the next line. A human can look at a paragraph of standard legal language, understand that it does the standard thing, and move on in a second or so; reading a paragraph of non-standard language makes the human stop and think, which is much slower and often causes anxiety.
Even better, there are usually many court cases establishing exactly how the standard language should be interpreted in a wide variety of circumstances, which makes the standard language much more predictable and reliable. In software terms, it has already been debugged.
I think part of it is that contracts are mostly interpreted by trained humans. A computer works through each line of code before continuing to the next line. A human can look at a paragraph of standard legal language, understand that it does the standard thing, and move on in a second or so; reading a paragraph of non-standard language makes the human stop and think, which is much slower and often causes anxiety.
Even better, there are usually many court cases establishing exactly how the standard language should be interpreted in a wide variety of circumstances, which makes the standard language much more predictable and reliable. In software terms, it has already been debugged.