Look at how hard it has been to eradicate diseases that only require a couple of doses of a vaccine. How feasible do you think it would be to provide daily prep to every male in the world? Even in developed countries with free vaccinations we are suffering from measles outbreaks in 2025.
Are those really developed countries? A decent free public school education is a requirement for a nation to be considered developed.
For diseases like measles, it's entirely due to human stupidity and society's unwillingness to oppose the stupidity and take the public health steps necessary to eradicate the disease. I agree with you. We're never going to complete any global public health project that relies on uninformed (or misinformed) people making voluntary decisions.