I think that the single biggest problem in this area is trust. If there is mutual trust between the party that is making the software and the party that is paying for it, that goes a long way. Otherwise, any kind of change will be treated with suspicion. One thing that agile approaches try to do is to bring these groups together into cross functional teams, so that the customers are involved in the day to day work. That helps a lot in building the trust that's needed for this approach to work effectively...
I think that the single biggest problem in this area is trust. If there is mutual trust between the party that is making the software and the party that is paying for it, that goes a long way. Otherwise, any kind of change will be treated with suspicion. One thing that agile approaches try to do is to bring these groups together into cross functional teams, so that the customers are involved in the day to day work. That helps a lot in building the trust that's needed for this approach to work effectively...
You're absolutely right. Trust is a major issue. That's why close collaboration and reliable delivery are so important.