You can catch flu from an asymptomatic person, but Covid has a much higher reproduction factor. During the winter lockdown in England, regular flu was completely eradicated - literally not a single case was detected in entire England [0]. At the same time, Covid was still spreading happily. The measures that stopped flu in its tracks only slightly inconvenienced SARS-Cov-2.
Covid is simply too good at spreading, compared to other similar diseases.
(As an analogy: I can swim, Michael Phelps can swim, we can both call ourselves swimmers, but we are not really comparable.)
[0]https://www.independent.co.uk/news/health/flu-cases-covid-en...