Carbon pounds

I read an article in the Guardian about Labour’s idea about personal carbon allowances that can be bought and sold.

One sentence struck me in this article: “[…] [It] redistributes money from the rich to the poor, from the frequent flyers to never-flyers, with a parallel currency.” A currency is exactly what this would be. I don’t understand what the actual difference is between this system and increasing green taxes while lowering other taxes. Or more concretely: Rather than giving each person a carbon quota worth, say, £1000, and then requiring them to spend carbon points when using fuel (directly or indirectly) and converting any unspent points to real money at the end of the year, wouldn’t it be much easier to give everybody £1000 extra cash (through the income tax system) and then increase green taxes?