In some states, only those seeking treatment are tested. In others, only those making an effort to be tested are tested.
We also did not start regular testing till last week.
How many Americans had experienced Covid-19 before last week? More than a few, right? We know people were infected and in the general population in the middle of February. That was 4 weeks ago.
It's interesting how much attention the published case count gets, but the unpublished estimated infected count has to be considerably higher.