As an economist I love this. People respond to incentives and making the decision visible, not making it a tax by letting the coffee shops keep the surcharge, and making it possible to keep prices the same (including the surcharge) is frankly a well designed law/experiment.
It's certainly a surprise for a government to go this route, though I'm not that optimistic.
If I understand it correctly, it just means that the surcharge needs to appear in the price listing, so I'd assume that customers will quickly learn to filter out that from their daily lives.
