Mail in ballots still need to get to the voter before Election Day. If the voter doesn’t deliver it to a post office or a poll station before Election Day it doesn’t get counted. Can you imagine how pissed people will be if Election Day rolls around and fewer than 50% of mail-in voters have been delivered ballots? Taxation without representation doesn’t go over well in the USA.

Yes, people can go to a polling place and file a provisional, but the whole point of mail-in is so we don’t have to. Also, with COVID affecting older people more than younger, there may be a shortage of poll workers.

Also prep time: The county election office needs a reliable estimate of how long the mail leg will take so they can target the process of printing and sending the voter package. They need to be able to print some of the packages on short notice for newly registered voters and party affiliation changes.

you may be correct - however, a lot of voter suppression is comparatively soft. more along the lines of discouragement. remove polling places, cause long lines, that gets on the news, people don’t bother to go after they get off work.

this could be similar, but for mail-in voting.

Many states have requirements that ballots must be received by election day.

I'm imagining massive pressure on Biden to concede before mail-in votes are counted, maybe combined with a 2000-style lawsuit that delays things even more.

Say I am an Oregon resident who can vote by mail by default. This election season, I'm stuck at my job site in North Carolina. I can request Oregon mail by ballot to my location in NC then vote and mail it back. As long as it is postmarked before the election ends I'm good and my vote makes it in to be counted.

But what if it takes 2 weeks to get from Oregon to NC then back from NC to Oregon? And then another week to be handled last mile and finally gets to the office? It gets to the right place and is counted weeks after the election ends and is effectively decided by most analysts. Or maybe it doesn't even get to me in time and my vote doesn't count.

Oregon I'd trust to open and count it accordingly as it checks all the boxes to be legit. But maybe another state is not set up for this process and hacks it together the month before the election. Maybe in that state my ballot doesn't make it to NC on time or even until after the election. Maybe once the ballot makes it home, it sits another 2 weeks in a backlog as a poorly funded, overworked team tries to catch up and confirm/reconcile votes across in person and this new mail in system. Maybe byt the time my ballot is done, it's the second week of December and the commission or Secretary of State isn't sure it has the right numbers and has to do a recount (or ignores it as clearly it's a broken system anyway, according to the president, so of course it would be off).

All of a sudden, we have another Constitutional crisis on our hands. The guy in charge has spread misinformation or full on fake news about an otherwise working system. He argued against and his party rejected any efforts to fund the mail in side of the national election even though it was openly attacked by foreign nations last time and is no more secure than then. Maybe GOP governors and secretaries of state who follow the president closely use his claims so that, due to expanded mail in voting, of course the numbers don't match polling or prior data so the election itself is a sham. Whether the numbers show Trump winning or losing, it's all a sham and can be ignored or taken before SCotUS which luckily has a few of your guys (Federalist Society picks) on the majority.

The dilemma is we need to oust any official who aims to undermine any government system or program, in words or actions, unless they are working on factually reported data and studies that indicate change is needed (which is almost always). The current administration has been lying to its citizens from day 1. Somehow that hasn't forced the resignation.

I wonder if this would run afoul of the USPS monopoly on first class mail?

The Congress makes the USPS fund it’s pension. No other part of the government has funded itself properly so lots of debt.