Its not only that they got a bunch of ballots from early voting but some states have stupid laws that all they can do is pile up the votes instead of starting to process. Which is why Florida went so quickly and other state like Pennsylvania is taking forever.
What process? The process the state doesn't start until election day?
The state doesn't operate a month's long/several months long ballot counting operation. They set up on election day, start counting when the polls close, and they finish when they finish.
Having a counting room going for a month or more creates a massive opportunity for ongoing fraud. If the window of opportunity is a matter of hours or a day, that's much less of a risk than weeks and weeks.
That's not even considering the labor costs to pickup, deliver, keep safe and count ballots over the course of early and mail-in voting.
Why is it "some people" have this belief that government can just pull a bunch of trained, well-paid employees out of a given orifice at the drop of a hat? This whole mail-in ballot crap was put in place in the last months of the election cycle with no planning, no budget and no solutions for the obvious problems. Every single problem warned of by the Republicans has now appeared in the aftermath -- just as the Dems intended.