Knowing what happened in a 1948 election is mostly irrelevant to figuring out what happened in 2020, other than "sure, in some election systems, fraud is possible." Lots has changed since then. Electronic voter machines didn't exist, new election laws were passed, and so on.
I'm not going to say that figuring out for sure what happened in 2020 is easy, but you do need to look at things that happened the same year.
It's not one of Carlin's, I think, but there's this old joke
Tech enthusiasts: My entire house is smart.
Tech workers: The only piece of technology in my house is a printer and I keep a gun next to it so I can shoot it if it makes a noise I don't recognize.
You slightly butchered the joke; how would a printer, by itself, be useful? Here’s what I believe to be the original:
> Tech Enthusiasts: Everything in my house is wired to the Internet of Things! I control it all from my smartphone! My smart-house is bluetooth enabled and I can give it voice commands via alexa! I love the future!
> Programmers / Engineers: The most recent piece of technology I own is a printer from 2004 and I keep a loaded gun ready to shoot it if it ever makes an unexpected noise.
While a funny joke, the point isn't really applicable here.
Parent poster, as I understood their comment, wasn't asserting that electronic voter machines are impossible to defraud. They were pointing out that you cannot reasonably make a comparison between elections 70 years apart because way too much has changed (one large change being electronic voting machines) for them to be comparable anymore.
The passage of time isn't an argument. If the only things cited are voting machines, then voting machines are immediately conceded as untrustworthy, no argument has been made.
Yes, it wasn't a full-fledged argument, more of a sketch. But assuming that how elections happen doesn't change over the years doesn't seem like a great default either?
I'm not going to say that figuring out for sure what happened in 2020 is easy, but you do need to look at things that happened the same year.