I think a major part of the frustration is more the _assumptions_ around the work complexity. Like decision-makers more easily make invalid assumptions regarding the complexity of the software portion. A good PM will listen to the SWEs when forming these assumptions and good SWEs must be able to communicate about them.
This could be bias talking, though. Is it common for sales or support teams to be given milestones that are off by 50%?
This could be bias talking, though. Is it common for sales or support teams to be given milestones that are off by 50%?