I agree with you that it's not strictly a "left" issue - and certainly the recent election in the US had the "right" bringing up voter fraud.
But it's important to remember the "left" raising flags about fraud in the 2016 election, and primary. Everything from harping on the legitimacy of a candidate that lost the popular vote, "not my president" protests, accusations of voting machine fraud, primary delegate issues, conflating gerrymandering with federal elections, etc...
In general, it seems whichever side loses is increasingly blaming "unfairness" to generate more outrage to de-legitimize winners of the election. ...rather than trying to appeal to more voters.
We're all losers in this situation because it is the voting system that keeps us from killing each other.
My only issue with this comment is that it seems to discount the idea of "unfairness" in our elections. Yes, in a federal election the districts don't matter. However, as we can see right now, the state legislatures that are elected via those districts can drastically change the landscape of a federal election within their state. The republican legislatures are moving en masse to "prevent fraud" in a way that seems to be directly aimed at making it more difficult to vote[1]. Appealing to more voters is hard when fewer people are able to vote.
If you believe only officially identified US citizens should vote, the left started attacking decades ago. Also, there was a strong 'Trump stole the vote' campaign 4 years ago, similar to the current narrative pushed by Trump supporters.
From the sounds of it, you think the beginning was 2020. There's a long history of implying the "other side's" win is questionable, across the globe and including the US.
