The question should rephrase to "Why Europe IT companies are not as prominent as USA IT companies"?
Do you think Bosch is a IT company(when they supply software to VW)?
European capital model and ways of doing business is the opposite of US neo-liberalism models. If you don't believe, you can compare Europe public own company capital with privately own company capital. Even things like loan facilities, Germany private owns credit union/cooperative bank(more than 1000) total asset is around 818 billion EUR (2015). Loan facilities from these "small banks" are mostly base on prudent loan criteria and credit records. So Europe society and the government basically favor prudent and organic growth.
However, this also means very conservative expansion. This explains why Northen Europe are less speculative. (with many historical lessons learned)
In addition, European private business owner also concerned about "meeting profits target", handle control over a board with huge shares. In addition, the profits target concerned also raise issues of "scorch and run" common practice in USA PLTD company, i.e. using mass layoff to boost profits per shares, which against the Europe societies values(with exception of UK, which scorch their industries under Thatcherism).