Why is a VPN for the professional graphic designers not pursued in the print-shop design?

A VPN would bring transport encryption, but it would also add another opening in the perimeter, and the disadvantages outweigh the benefit.

The idea was to give the regular professional customers VPN clients so that their files arrive through an encrypted tunnel. But the threat is malicious content in files, not eavesdropping on the way, and a VPN does nothing to inspect content. It would instead bring outside machines, which the print shop doesn't control, into its network, adding one more door to look after for a small company with limited resources. The case was to be solved with the focus on content control.

Go deeper:

• Virtual private network — Wikipedia — tunnelling, encryption and the main VPN types.
• Content Disarm and Reconstruction — Wikipedia — rebuilding incoming files without their active content, a strong form of content control.