UBI will be nothing more than the current welfare program expanded. And if you think for a second any government will financially approve any more than BASIC bread-and-cheese income, you're delusional.
Yes, it will be a sort of welfare program. But the Finnish are planning a model experiment with UBI anyway, with the UBI being slightly higer than the current welfare rates. There is your government that at least considers the possibility.
And I think the Finnish approach makes sense. There is a growing part of society that won't get a job again, due to automation increasingly killing low-income jobs. Now in most of Europe this means a lot of bureaucracy for making sure that only really poor people get welfare. The finnish government expects more savings on the bureaucracy then the increase in UBI over the old welfare rates will cost.