Yes, but by the time the system is implemented, the official whose pet project it was had moved on. The new official wants to channel resources to his own pet project, not making the old one work.
Or, alternatively: When the system is originally contracted, the bean counters refuse to permit any budget for any development beyond the initial creation.
You're exactly right. Officials like to award contracts for new systems--it makes them look important, it gets the systems integrators to kiss up to them, and the failures won't become apparent until they've moved to their next job.
The question is whether the workflow the developers are being told to implement is what the workers actually need to do to get the work done. Also, will there be an ongoing mechanism to revise the software as the work requirements change? In most cases, the answer to both questions is no.