Why there are no famous software/IT companies in Europe? (unlike USA) Both USA and Europe have highly developed economies with famous car, aircraft, food, oil etc. companies.
However, when it comes to IT - 

USA has Google, Facebook, Amazon, Dell, Cisco, Microsoft, Red Hat, HP, Apple etc.
Europe has... nothing? (Nokia is dead)

Why?
In Europe there is typical more regulations and more and higher taxes on profits, financial transactions, and on products and services. This means there is less incentive for entrepreneurs to create their businesses since they face for example higher yields and higher interest rate coupons, environmental regulations, state bureaucracy which increases the cost and decreases the incentive (profit). Since most of innovative companies are generally start-ups such as Facebook was, there is higher cost of funding once these companies are considered riskier. In Europe that cost is further increased by the tax system for example.   There are also other factors such as education quality that differs. Europeans generally regards the US universities to be more prestigious and this is a decisive factor that makes lots of Europeans, typically the brightest to migrate to the US for further studies and higher wages since Americans can afford to pay more since there is less state interventionism.
I hope I gave you some ideas of what might be going on. In economics there is no definitive answer so keep on investigating and asking other people. Sorry for the lack of data.