Each of these illnesses has its own unique challenges and cannot be compared against one another. Just because scientists haven’t been able to develop a vaccine against HIV after several decades, doesn’t mean they needed as long to create a COVID vaccine. It also doesn’t mean a vaccine produced more quickly is somehow fraudulent or dangerous.
Developing vaccines for some disease-causing viruses can be complex. For example, the virus that causes HIV can hide and make itself undetectable by the human immune system, which makes creating a vaccine for it extremely difficult.
The common cold, on the other hand, can be caused by any one of hundreds of different viruses, so a vaccine for just one of them would not be very effective.
SOURCE: https://www.hopkinsmedicine.org/health/conditions-and-diseases/coronavirus/covid-19-vaccines-myth-versus-fact (Johns Hopkins Medicine)