These aren't actually charity workers.
They are contracted by a big corporate company that manages the people and the money gets sent through them to the charities.
I had an interview with a company like this before. They made it sound like an amazing job on paper and at interview but in reality it was knocking on doors and asking for people to sign up to direct debits to charities as they get commission for every direct debit.
All of the employees are "self-employed", and if they don't get any sign-ups in one day, they don't get paid.
The bloke that took me round for an "introductory day" lied to people, made out he had kids to get sympathy and people signing up, even said stuff like old people were more likely to sign up, and he bought his cigarettes from small newsagents that didn't itemise receipts so he could pretend it was "lunch" and claim it as a business expense.
At the end of a very long day trudging around they asked me if I wanted the job but I told them to stick it.
I have no good words to say about the company, they're not in it for the charity, they're in it for lining their own pockets.