You're probably 15 years old or thereabouts, so I'll keep this simple:

With UBI, you will have to drive your trash to the nearest landfill yourself. And the car will barely work for lack of mechanics. And the road will barely function for lack of construction workers. And the landfill will just be a disordered rubbish tip, and not a proper facility. Because no one--and I mean no one--is working in garbage, grease, or tar when they can sit at home instead.

It's the purest idiocy anyone ever thought of.

And yeah, doctors and nurses are in it for the money. No one works in shit and puke for fun either.