We are sometimes asked about various ISO standards registration and why we have not been certified. The answer is that we do not believe that these standards are appropriate for ourselves or our clients.
The bit about or our clients often confuses people, if I want you to write me some software, then how you do it is up you.
Actually no, most quality systems require that you measure you output against a specified standard, in the case of software it is usually against a Functional Specification.
The problem is always who creates the Functional Spec, in general you as the client probably don't have the time or expertise, if you had the expertise you would probably not be outsourcing the work.
If we create it then the software will match the spec but may not do what you want. It's a lovely spreadsheet but we wanted a word processor.