What are the reasons that projects frequently do not meet customer expectations?

Customer satisfaction depends upon a project, product or service meeting their expectations. This will fail if the technical aspects are inadequate, that is, the product or service did not perform the explicit and implicit expectations of performance. Explicit expectations are mental targets for how a product performs, and there may be well-identified performance standards for customers to judge this against.

Then if a contractor has not built in capability for risk management there is likely to be a proportion of dissatisfaction amongst customers at best. Unclear scope management by the customer should not be used as an excuse. It is for the project to explain scope clearly.