For one thing, coronaviruses are known to mutate heavily, which is why they've never been able to create a traditional vaccine for them.

Flu viruses are comparatively stable and their vaxes are traditional, ie, use actual virus (inactivated), so all different types of viral proteins (potentially thousands of them) can stimulate antibodies. If one protein mutates there are still plenty of antibodies that will be effective against the other proteins .

These new faux vaccines inject artificial rna or dna to instruct cell ribosomes to quit their day jobs & instead synthesize a toxic spike of 4-5 proteins (which happen to closely resemble normal human proteins) for an unknown period of time. The mutation-prone coronavirus needs only a small mutation or 2 to outmaneuver the faux-faxes few antibodies.

Additionally, Fauci spokestwinkie claims they modified the spike so it can't "do all those things" that the Salk Institute proved it does, the primary thing being binding to ACE 2 receptors.

If true, than the antibodies that the modified spike stimulates will be a poor fit for the real spikes.