Your point is valid and correct as I have also been down the same route in trying to get hold of the fuse layout diagram. The retailer couldn't supply this info, nor was it in the owners manual.
I called VW UK on 0800 333666 to raise this, they advised that due to the techincal advancements in the cars today, they could not accept liability if something went faulty as a result of a fuse being changed based on their diagram.
They pointed me to their ERWIN site http://www.erwin.volkswagen.de where you would have to pay to access the details. I think a one hour access costs about €5.00 which I think is a complete rip off considering all other cars I have ever bought already had the fuse diagram supplied in the car or Owners Manual or both.
Alternatively they suggested that I take my car into the dealer at my cost as fuses are not covered under warranty.
I have escalated this to VW and am waiting for a reply.
FYI I know you only mentioned it as an example but if the front wipers fuse popped, it is likley to be the 10a fuse at Fuse location 2 (Washer Pump) the associated fuse for the Wipers is location 47 which is a 20a fuse. I had to change Fuse 2 and mine started working ok.
The horn is positioned at location 46 (20a fuse too).