Huge amounts of government money gets sucked away in the bureaucracy required to ensure that recipients meet the requirements of whatever the the program is, and trying to ensure that no-one receives funds to which they’re not entitled. If a UBI is universal, based on (e.g.) you’re a citizen, or resident for > X years, and over the age of Y, you qualify. Administrative overhead becomes negligible and significantly more of the funds allocated to the program go to the recipients rather than to the administrators/auditors. Granted it may reduce public service employment opportunities, but that’s a good thing isn’t it!