Why are shipping prices so different between different country's Amazon sites?

[jacobsever]

Shipping for a single steelbook from :

Amazon.fr - 8.99 EUR ~ $10.02
Amazon.de - 3.72 EUR ~ $4.15
Amazon.ca - 8.29 CAD ~ $6.68
Amazon.es - 9.41 EUR ~ $10.49
Amazon.co.uk - 3.08 GBP ~ $4.73
Amazon.it - 10.41 EUR ~ $11.61
I get that they are different countries with different post offices...but still, it's all the same company. Amazon. I wonder why there isn't a more standard international shipping base price.

Seems strange to me that things would range between $4.15 - $11.61 to ship the same weight item.