My family once had to navigate Medicaid. I was well-resourced, understood the expected outcome thoroughly, was motivated to get it done, and committed the time to follow the required process. When our initial application was mishandled due to inaccurate guidance, it took over 2 years of persistent failed communications with the various county, state, and federal agencies, back-office middlemen, doctors, and legislators to get any response beyond "apply again and hope for the best", which we did several times to no avail. In the mean time, having a Medicaid application open changes the availability of medical care, as some doctors will not or cannot by law accept additional Medicaid patients. Eventually by some mild social engineering I procured direct access to a specific empowered bureaucrat who had knowledge of a separate set of applicable rules/processes and resolved our case immediately.
Most people in poverty do not have the time, attention, or stamina to persist through means testing on top of struggling against whatever landed them in poverty in the first place. Every time I visited the county office, I would hear someone complaining about how they had applied 8 times without success for a program everyone in the room agreed they should qualify for. Means-testing is designed, by popular demand, to make accessing benefits difficult for the sake of spending less. UBI, for all its faults, at least addresses that problem.