Is tzadakah an obligation of the individual or the society? Assuming – as I do – that it’s the former, then no government involvement is needed, unless the topic is enforcement.
The Torah supports Capitalism, not Socialism. Taxes imposed by a king are paid by the individual, not the kingdom. Terumot, Maasrot, Lekket, Shichacha, Lending, etc. are taken from the individual’s harvest or possessions.
But, because the elected governments in our day enforce tax collections which result in astronomically large pools of money, people daydream of limitless funds from which to pay for every worthy cause. Yet, even astronomically large pools of funds are finite (unless, of course, one piles unbridled borrowing on top of the mix. Then, suddenly, the discussion moves from mere daydreaming into the delusional).
Sure, one can provide unlimited food, clothing, shelter, healthcare, education, transportation, police, fire, sanitation, courts, jails, armies, mail, street lights, paved roads, etc. without regard to ability to pay, age and citizenship. But, someone (or a lot of someones) has to pay for it all.