Probably all of the above and more reasons besides. It appears as if people convinced themselves it was all over and got careless in many ways.
What if it turns out that being "careless" allows the virus to "rage" through the community faster and get it over with sooner? Otherwise, you forestall the damage as everyone stays locked up. m Then when you come out again two months later, it starts spreading again. Sure the statistics look worse initially. But if the end results are comparably the same, you've only hurt the economy worse by delaying. Pay now or pay more later.
Additionally, and unfortunately, this is election season in America. So both sides are making arguments and instituting policies that are politically measured. The poor public, sick, confused, and poorer, just throw up their hands and say screw it. Sometimes doing something, anything, is better than doing nothing. At least for many of them.