Well said, Nina. I'm an accountant for a national charity - accounting for charities is actually a lot more complex than for a lot of private companies, many of whom I have also worked for - and I get paid what would be considered a "good" salary by very many people.
It is, however, a lot less than I could earn (with my experience and qualifications) in a similar job that wasn't in the charity sector, say around 25% less than I could earn in a media company or something.
The simple fact (and it's a sad fact) is that if charities were to rely purely on volunteers to do the work that needs to be done then many charities wouldn't exist. They do need specialists, and specialists deserve to be paid. Likewise, charities still have bills to pay - insurance for those volunteers isn't free. They have to pay for rent, utilities, equipment, and they have to pay VAT too - they don't get everything for free just because they're charities.
You are never going to find a single charity anywhere that spends 100% of the funds it raises on its causes. It is, sadly, impossible. It costs money to run a charity, even a tiny one.
The government, at the moment, is trying to turn us into a "big society", where we all help each other without government funds being used. This means that (for example) medical charities are now increasingly taking over some of the functions of both the NHS and the Dept of Health at a time where donations are going down because of the economic downturn, and many charities have lost their government funding altogether. However, medical charities in particular can't just stop doing what they do because people lose their lives.
So, yes, charities are increasingly trying to raise more money from ordinary people, and yes, it can be irritating, but would you prefer charities sent you letters whining about how unfair it is that they have to do more now with less funds, and it's the governments fault? I wouldn't.
And frankly, charities only staffed by the people who can afford to work for "free" wouldn't be doing much good. Think about it.