The prices are not that different. They're just being shown differently.
Taxes in the US are lower and the taxes are collected differently. In the US
the taxes are collected at the end of the purchasing process whereas in
Europe they are included in the price shown of the product.
As an example:
A US receipt:
$50 USD WIFI ADAPTER
$10 USD Tax
-------
Total price: $60 USD
European receipt:
$60 USD WIFI ADAPTER
--------
Total price: $60 USD
There is some adjustment to compensate for our cost differences as well. The
shipping was cut in half for example (roughly).
In any event you're also not taking into consideration all the 'free'
services your getting from the higher prices. In the US people who go to
college have to pay back student loans and health care isn't covered by the
government. Many people have to pay thousands of dollars every month for
health insurance, student loans, cars, car insurance, and other similar
expenses. Cars in the United States are not a luxury in most places. They are
essential as there is no public transportation.