Before revision:  I hypothesize that this can be traced back to a self-selection bias in testing . To explore this hypothesis , I extend the classical SIRD model to incorporate conditional quarantine and  two groups of agents : the majority and the corona sceptics, where the latter are less inclined to get tested and engage in social distancing.
After revision:  I hypothesize that this can be traced back to a self-selection bias in testing , which causes a higher dark figure in FPOE strongholds. I find empirical support for this hypothesis in individual-level data from a Covid-19 prevalence study showing a much higher share of (undetected) cases among "corona skeptics". I finally extend the classical SIRD model to incorporate conditional quarantine and two groups of agents : the majority and the corona sceptics, where the latter are less inclined to get tested and engage in social distancing.