Again, that is simply not the case. At all. State governments[1] run several elections every year, and they use the same processes and laws for all of them. Surely you've voted many times since 2020, right? And probably before, right? And... you didn't notice that it's the same process?
[1] This was not, and has never been, "an election" that is "administered" in a central way. Every state has its own laws. Every state runs its own election. The only federal "election" involved is the ceremonial one involving the meeting of the state electors.
> This was not, and has never been, "an election" that is "administered" in a central way
The lack of central administration is the primary source of skepticism. States and regions each determined their new rules independently without formal oversight or approval. A single nationally-run election would have ensured everyone followed the same rules, even if those rules weren't perfect or to everybody's liking. Without that, all kinds of rumors and stories and misunderstandings were reported in the media, regarding different local rules around mail-in ballots, signature verification, drop-off boxes, counting procedures, polling hours, etc. Even if jurisdictions followed their own rules perfectly, it led to questions about why those rules were set that way in the first place. People in California thinking Florida is rigging things, while other people in Texas assuming Michigan is corrupt, etc etc all over the country, mostly based on unsubstantiated rumors and media reports, but influential nonetheless.
If you haven't read the Michigan Senate report (result of an 8-month bipartisan investigation chaired by a Trump Republican), please do. It cleared the air and answered tons of questions for me, seeing the evidence they found and realizing that there are simple, understandable reasons explaining what happened and also explaining the ruckus that resulted from so many people crying fraud but being unwilling to take time themselves to investigate the facts of the matter.