Talk about stupid !!!!!
There is a very simple answer to this, and your examples of a camera and a manual are ideal to illustrate it.
If the seller does not specify the weight and dimensions of the item, the GSP applies an average figure for items in that category. If the manual was listed in the camera catagory, as they usually are, then without any information to the contrary the GSP applies the average shipping cost for that category and you get the result of the camera and the manual costing the same to post.
If the camera manual seller had filled in all the details, the shipping cost would have been much lower. This is the sort of advanced stuff that users simply do not know about. They assume, for example, that because their item is 'free' or flat rate shipping, they do not need to fill in all the details for the shipping calculator. A reasonable assumption but in the cases noted above, the answer is often obvious when you know how the system works, and you can see why the shipping is so high.
(Not guesswork but solid information about how it works from a senior UK GSP person.)
Obviously sending one playing card is an absurd use of the program, indeed, sending any item inder 2 kilos is usually an inappropriate use of the program. It is an open argument whether the GSP sellers are to blame for not understanding how to use it,or ebay is to blame
for the lamentable failure to educate users properly, and to implement the software fixes (mandatory fields for sweight and size) that would solve the problem.
It is not really stupidity of the system, if anything it is the stupidity of the sellers and the designers of the listing software.
Now that you understand how these very high costs are generated, it should be easy enough to spot examples, like some above, where it is clear that the average category weight must be much higher than the specific item with the silly shipping price.
Trying to persuade ebay that this is a real problem, that they could cure if they wanted to, is quite another thing.
