For most software I've seen, it's a handful of (really complicated) requirements that balloon the cost by orders of magnitude. Making a piece of software? Easy

For most software I've seen, it's a handful of (really complicated) requirements that balloon the cost by orders of magnitude. Making a piece of software? Easy! Integrating with one external provider? Okay... yeah we can do that. Integrating with an arbitrary and ever-growing number of third parties? Gulp.