[carlosjobim]

There's several rationales:

1. They need to tax every economic transaction possible to maintain demand for the Euro currency and keep it from loosing its value. This is the most important reason.

2. To get more money in taxes for the government. There's people who argue that lower tax rates increases economic activity and in the end would increase tax revenue also for the government. The government doesn't see things that way. "You pay me now, pay more!"

3. Taxes on profits are an incentive for business owners to reinvest any surplus into growing their business, meaning more jobs etc.