TOTW: why do companies charge for non-plastic bags ?

On a recent trip to the Body Shop we were asked to pay 5p for a non-plastic bag, we queried why we were paying 5p for a non- plastic bag and we were told, because ‘they have to pay for it’. Which had us wondering why exactly are we charged for non-plastic bags and where are the funds going?

The Body Shop charge us 5p for paper bags which are made from 100%, recycled materials and produced using environmentally friendly water-based inks. The 5p cost is said to go towards the cost of making the bags. 

#FLODown: We are 100% on board with the shift to making everything as environmentally friendly as possible. However, after purchasing a 200ml tube of cream for £15, a free bag would be much appreciated.