Economists have long known that negative income tax (which is equivalent to a guaranteed basic income) is theoretically optimal under the usual assumptions of perfect markets and perfect rationality. However only very few economists, such as Milton Friedman, have advocated it as a practical policy.
On the one hand, guaranteed income is much more resistant corruption, since the distribution of money follows a simple rule where there is no discretion on the part of officials, and is similarly resistant to other kinds of rent seeking.
On the other hand, through traditional welfare systems, governments may be able to determine who is really in need, and thus save money on giving out welfare to people who could be earning more if they had to. Governments can also give out welfare in kind rather than cash, helping people to make better choices, or make welfare conditional on getting education or training.
I very much doubt that a negative income tax could improve over the best administered welfare systems such as Australia's. What is interesting is whether countries with much less ability to administer public services, would be better off with a guaranteed income.
* determine who is really in need
* helping people to make better choices
seems absurd to me, and more a defense of the guaranteed income than a critique of it. Faith in perfect markets is hogwash, but so is this level of faith in bureaucracy; even a wise individual would have trouble making these kinds of judgments personally.
E.g. when you provide people with free healthcare instead of giving them money, your are implicitly constraining their choices. Same for food stamps, free public transport for the poor, etc.
Determining who is in need means, for example, not giving welfare to people who are not genuinely searching for work. This is a difficult decision to make but it is done fairly well in Australia. It is mostly based on objective criteria e.g. filling in a list of places where you applied for work, showing up to interviews that are arranged for you.
I suspect that your objection is not to the general principles listed above, but rather to listing them explicitly without any disclaimers like "I know the government often gets this wrong" etc.
On the one hand, guaranteed income is much more resistant corruption, since the distribution of money follows a simple rule where there is no discretion on the part of officials, and is similarly resistant to other kinds of rent seeking.
On the other hand, through traditional welfare systems, governments may be able to determine who is really in need, and thus save money on giving out welfare to people who could be earning more if they had to. Governments can also give out welfare in kind rather than cash, helping people to make better choices, or make welfare conditional on getting education or training.
I very much doubt that a negative income tax could improve over the best administered welfare systems such as Australia's. What is interesting is whether countries with much less ability to administer public services, would be better off with a guaranteed income.