Sorry, call me cynical, BUT Charity Shops only want Vollys as FREE LABOUR , to keep costs down, and to pay the HIGH SALARIES of their Directors !!!
Spotted in the window of a local charity shop was this clever poster which captures the two main reasons why people volunteer:
People help both for what they get out of it (fun, learning a new skill, meeting others and so on) as well as what they know the cause gets out of it. Appealing to both motivations is what gets the most help (as explained further in Chapters 26-29 of 101 Ways To Win An Election).