I know it's expensive. I work for a company that designs switching power supplies. I do the printed circuit board layouts that have to meet many UL and CSA specifications for creepage and clearance distances as well as meet flamability standards. We can't ship a single product if it's not UL/CSA approved.
I've had my DC4 apart to check it out. Everything looks good from a safety point of view. Fuse protected AC mains, wire gauge is appropriate for the currents flowing through them, FR-4 circuit board material, quality relays, plastic box to reduce the risk of shock, etc. I'm a little concerned about the melting plugs though.