I suspect it grew out of electrical engineering. Machines/parts could only return errors as integers, so you would expect people to open up the documents and r

I suspect it grew out of electrical engineering. Machines/parts could only return errors as integers, so you would expect people to open up the documents and read that error code 1021 meant that the unit had caught fire. Software just kept the tradition of error codes, since that meant you could also sell that juicy documentation (localized into whatever language you wanted) to the user as well. I suspect it also a localization issue because OracleDB would never return the table/column in the error message, so as to be easier to translate.