Why would this be desirable? To use the US as an example, If you cut food stamps and medicare/medicaid and social security and just paid everyone 10 thousand dollars a year straight up you would have eliminated much of the need for those social programs and saved money on the administration of them as well as eliminate the prospect of committing fraud. You would need to administer this transfer of a couple trillion dollars in an efficient manner though, so it's unclear if any actual savings are brought there, and you need to raise taxes obviously as well (though by less than you might think - if we pay 10,000 dollars to 200,000,000 adults that would be 2 trillion dollars in spending - if we eliminated medicare/medicaid and social security, we would cut about 1.6 trillion dollars, so we would need to raise another 400 billion dollars a year in taxes, which is significant but not outrageous in scale). Keep in mind that when you raise taxes you're raising taxes on people who are being paid 10,000 dollars extra a year - mostly the tax raise would just be to make it so that people who are being paid a good amount already get taxed an extra 10,000 dollars to cancel out the extra 10k they are getting (so effectively fewer adults would really be getting paid 10,000 dollars a year)