Just a few quick examples from one quick search. To say there is no voter fraud or the risk, with mail-in ballots is minimal, is just mis-stating the facts. If it happens once, it's far too often. The California example cited is the most egregious and involved multiple thousands of votes, mail-in style, that magically turned up days after the polls closed.
In New Jersey in 2013 -- not in 1813, 2013, a city councilman was caught paying operatives to go door to door telling people who to vote for and offering them $50 bucks. Texas as had multiple prosecutions for illegal vote harvesting.
In 2016, council member Guadalupe Rivera won a local election by 16 votes. Later, Rivera was convicted of illegally assisting people in filling out absentee ballots. According to the county clerk, ballot harvesting fraud involves political operatives who target and exploit the vulnerable -- often that means homebound individuals were too confused to realize their votes are being stolen.
In California, ballot harvesting is already almost totally unrestricted. In the midterms in 2018 officials in Orange County reported people dropping off hundreds of ballots at a time. 250,000 votes appeared from previously inactive voters.
From, of all places, MSN via CNN -
What a West Virginia man says was a small, joking attempt at voter fraud shows just how closely officials are watching
1982
An estimated 100,000 fraudulent ballots were cast in a 1982 Chicago election. After a Justice Department investigation, 63 individuals were convicted of voter fraud, including vote buying, impersonation fraud, fictitious voter registrations, phony absentee ballots, and voting by non-citizens.
