While I'm sure the Smith Family does wonderful charity work, their ads are an absolute travesty. Government Schools just don't work like they portray...
If a family can't afford books, the school will provide them. This includes pencils, paper, books, whatever. If the kids doesn't have a proper bag (seriously Smith Family? - a plastic shopping bag???) the school will go and buy one, admittedly a cheap one from Kmart or such, but a proper bag.
As for the uniform the school will also provide these items if the kid isn't dressed suitably, on a loan basis.
Paying for an excursion is optional in all government schools. It is not compulsory and if parents can show good reason for why they can't pay, then the school will waive the fee and the kid gets to go.
Same goes for the government schools tuition fees. These can be paid in installments or waived altogether. In WA the annual government school fees are not compulsory and only about 40% of families pay them each year for any typical school.
The Smith Family TV Ads are an absolute crock, designed to tug at your heartstrings and of course make you pay them money (which like a lot of charities, the bulk goes on 'Admin fees" to maintain their own existence). It drives me wild every time I see them on TV.