IOW, developing vaccines should be straightforward. Except that we have demonized the pharmaceutical industry to the point of near extinction. No one will ever make a penny developing the vaccine, and the sniveling ingrates will sue them out of business because it doesn't prevent cancer.
Add to that the anti-vaccine fanatics who call vaccines "toxins" and loudly decry the pharmaceutical industry for pushing vaccines only for profit. They will do their best to dissuade people from taking the vaccines, and too many people fall for it.
Vaccines are not profitable. A lot of vaccine development takes place at universities and small start-up biotechs (probably funded by "angel" donors); pharmaceutical companies won't take on development of a prototype until the small biotechs or university labs have already done the costly groundwork of weeding out the non-viable protovaccines.
Of course, vaccine development is costly--just like any other drug development. People who deride "big pharma" profit always conveniently leave development cost out of the equation.