Robin Hood made his mark robbing from the nobility – wealthy landowners and such – and sprinkling the proceeds among the subsistence-level workers, or so the story goes.
In that regard, calling a tax on financial transactions a “Robin Hood Tax” is a bit of a misnomer. Such a tax burden would not be shouldered by the supposed rich banking barony, but rather by the retail end users and the institutional investors who manage and invest on behalf of pensions and retirement accounts. In other words, the “little guys.”
True, such a tax would harm the banks, brokers, exchanges and service providers doing business in countries subject to such a tax, but it would likely ignite an exodus to friendlier tax regimes. When that happens, there will be fewer transactions to tax, and less overall revenue flowing through the sector and into the local economy. That idea does not sit well with Christian Noyer, governor of the French central bank.

“I do not believe it was ever the intention of the French government to do something that would trigger the destruction of entire sections of the French financial industry, trigger a massive offshoring of jobs and so damage the economy as a whole.”
– Christian Noyer, French central bank governor, on the proposed financial transaction tax

For what it’s worth, the truest form of a Robin Hood Tax is a progressive income tax. France already has one of those.