Because they are not collaborating in real-time. By collaborating in real time, engineers and customers iron out the details of product development and create the perfect product the first time. SolidWorks engineer invites the participant to a collaborative session. Participants rotate the model and can highlight a certain area that needs further examination. Participants suggest changes for the engineer to make.
Engineer sends the new version of the product model to each participant.
Participants approve the change, and the engineer moves forward in the design process. E-mail the participant an invitation to the collaboration session. Participant double-clicks on the invitation, and the session begins. It is so simple to use, all the participant needs is a 500k viewer, e-mail, and an Internet connection. The participant doesn't need SolidWorks.