A significant issue for workers is that companies want cheap labor. They profit off of people not knowing their worth or needing money no matter how low the pay. This poverty trap continues to increase as the rich get richer, but the poorest in society gains nothing.
As things are, UBI is not practical, with or without other welfare programs. Being a welfare program itself, the main problem with implementing it is that most assume the rich will be taxed to pay for it. In reality, it would replace welfare programs people already have in place.
It cannot completely replace all welfare, and even only replacing a few welfare programs complicates things. Welfare does not provide economic freedom; it provides economic aid. If implemented, the welfare structures it replaces benefit programs and deductions, including the ability to write off medical expenses and business loses.
With large companies, this shouldn’t be a problem, but for small businesses, the cost increases exponentially. To work together with welfare would change the game, but it’s important to know what would stay and what would go.