Is it not understood that "absentee" and "(universal) mail-in" are not the same things? Is it not understood that saying "mail-in" voting refers to universal mail-in voting and not to absentee voting?
The entire point of the debate/discussion is that absentee voting is not the same thing as mail-in voting, and that the absentee ballot infrastructure/workflow is not a proxy for universal mail-in ballot workflow/infrastructure.
I would also like to see some attention to the magnitude of the problem. Universal mail-in voting will require processing many orders of magnitude greater amounts of ballots, and as such all numerical aspects will be equivalently magnified. Beyond the potential to simply overwhelm the system in place, that tiny percentage of fraud so oft referenced would also be magnified by those same orders of magnitude. Does 100x the amount of historic fraud become significant? What about 1000x?
Take the example of NY state. The 2018 general election, conducted under rules allowing only absentee ballots granted due to an accepted excuse, rejected 14% of those ballots submitted. The more recent example of NYC relaxing the rules governing absentee voting to require no approved excuse resulted in a 10x increase in requested ballots, the rejection percentage jumped to 21% of all mailed ballots and official results were delayed until after the election by up to one month
I see no evidence that any locale that doesn't already have mail in voting online will be in any way ready to implement such. Perhaps start just after November 3rd with the goal of being ready by 2030