It's not fair your friend has to pay.
It was careless that the money was left there unlocked while people went somewhere else outside to talk..however nothing might have happened.
As for why the money was transported all over town or whatever or counted many times...hard to know. But some people can also be incredibly naive...especially for volunteer fundraisers.
I guess with the volunteer organizations I've worked for in past few decades, it did help to:
have a treasurer
cheque signing authority limited to only 1-2 people in volunteer organizations. (usually people such as treasurer, president or vp)This is requirement of any Canadian bank for organizations. It's these people in the end, who physically hold the money and can make deposits into the bank or withdrawals as deemed by organization. A slightly demanding role for an organization, but important.