If national productivity is insufficient to fund a basic income, how has a basic income been needed for some time? One of the assumptions of basic income is tha

If national productivity is insufficient to fund a basic income, how has a basic income been needed for some time? One of the assumptions of basic income is that automation will displace so many jobs that people will be redundant. But if the economy cannot fund basic income, then not enough people have been displaced yet, and there isn't enough automation.