Patent claims and fraud

Of course, it would be best if patents like the one described were consigned to the dustbin, but with the "inventors" and/or patent trolls having nourished themselves through this invalid patent, potentially knowing that no act of "invention" (even by the ridiculously permissive standards of the patent regime in question) had taken place, due to prior public knowledge of the techniques upon which the patent was based, might it not be appropriate to consider the actions of the patent holders as fraudulent?

If someone were to request that you pay them a tax, claiming that they had the authority to demand that tax from you, and after having paid that tax you were to discover that that person had no such authority, would you not under any other circumstances be able to demand that they be prosecuted for fraud? With frivolous patents granted continuously (in areas where no patents should even be permitted) and with no disincentive for patent holders trying their luck, is it really a surprise that we see a parade of thinly veiled extortion attempts from one day to the next?