The bank screws up and the people with the accounts are the ones who literally pay for the bailout. It's happened before in different ways and it's why most people hate bankers. The extra shocking news will likely be that the people at the top of the employment chain will get a bonus this year for "saving their bank"
There is a small point you've omitted though; they won't just be taxing people with savings under 100k, but also people with saving
over 100k by 9.9%
http://www.bbc.co.uk/news/world-europe-21821155