I wouldn't even call it "very very very good vaccine". It's just a different problem each vaccine has to solve. Some problems are inherently harder: flu, coronavirus, hiv
Making a vaccine is more straightforward (ie we expect to be able to) when we know there is a response by our own immune systems - hence we expected to be able to make a COVID vaccine (although the time scale is still an amazing accomplishment - thanks 20+ years of mRNA research!). And we are still working on a vaccine for HIV.