Universal basic income is a heated issue precisely because it purports to accomplish so many things. Typically, whenever we ask too much of one policy instrument, it falls short. According to Guy Standing's opener, UBI will free us from the constraint of having to work, but also of being told what to do and by whom. But these freedoms will only be realized if the basic income is at such a level that our material needs are completely satisfied. One can’t walk away from a nasty boss unless that job really isn’t needed. He states that the UBI should not be a substitute for existing public services and that groups that are constrained in their earnings (disabled workers, the elderly) should receive supplements. People are thus still working, providing “essential services” for our societies. So what is compelling them to do the paid work? While some jobs satisfy other human needs that people derive pleasure from, many jobs do not (sanitation workers, janitors, bus drivers). UBI supporters would argue that by providing economic security, the UBI will increase bargaining power to such an extent that the less desirable but still needed functions performed by workers will be compensated at such a high level that it would attract workers.
But I think another scenario is more likely: the UBI will not be sustained at a high enough level to fully remove the need to work. The history of capitalism is replete with examples of coercive measures taken to create a labor force. Perfectly content and self-sustaining indigenous communities were enslaved or deliberately deprived of their land in order to make them work. I see no reason why it would be any different now.
In the capitalist system in which we live, the UBI would succumb to the same pressures. It would be kept low enough to eradicate hunger, but not much else. People would have to work (as most jobs cannot be replaced by robots, and even robots need humans to operate them). The result is that the UBI would act as an unconditional income supplement, similar to the child grants and old-age pensions that exist in many countries today. There is nothing wrong with this, and the unconditionality and universality of such an income supplement is a welcome feature, but then we are not so free, and little about our society has been transformed.