The public lists contain names and addresses.
I might type in my deceased grandmother’s name and see that her vote was counted last night at 4:00 AM. Or I might type in my street and notice that my old neighbor who moved out of state 2 years ago had his vote counted at the same time. We now have clear evidence of fraud.
You might know about your neighbor but how do you track every mail in voter ? Are you going to contact a half million people ?