Perhaps they're estimating reinfections of first wave mild cases, which were rarely confirmed by testing
That would be interesting (and a reasonable thing to do), but then it would be astonishing if it was only "up to 10%" as that means they're detecting 80 odd percent of re-infections. And whilst I do think you're probably a bit more likely to test positive if you've tested positive before (as in if you're positive, detecting the second case is more likely if you detected the first because you've already shown you're motivated to test etc.), But I don't logically think the rate would be that high, that's super high. I'd've actually thought it would still be much around the 50% mark of case detection that's been implied in the seroprevalence reports.
France is astonishing numbers I think, I thought they had a reputation for low compliance with covid, but reported over 300,000 cases today? (no obvious lag as that's just a small growth from others) You would've thought detection would not be that high in the reputation?
Germany has certainly joined Netherlands with rapid growth despite lockdown. Still haven't been able to find anything on if this is general disobedience on the rules or that the rules are not enough.