Because they can't win if they don't cheat - Part whatever

The California Republican Party has admitted responsibility for placing more than 50 deceptively labeled “official” drop boxes for mail-in ballots in Los Angeles, Fresno and Orange Counties — an action that state officials said was illegal and could lead to voter fraud.

The dark gray metal boxes have been popping up over the past two weeks near churches, gun shops and Republican Party offices, mostly in conservative areas of a deep-blue state, affixed with a white paper label identifying them as either an “Official Ballot Drop off Box” or a “Ballot Drop Box.”

To the average voter, they are virtually indistinguishable from drop-off sites sanctioned by the state, which are governed by strict regulations intended to prevent the partisan manipulation of ballots.

[...]

California’s secretary of state, Alex Padilla, and Attorney General Xavier Becerra sent a cease-and-desist order to the state- and county-level Republican parties, ordering them to remove the boxes. They also urged voters who might have unknowingly dropped off their ballots in the receptacles to sign up with the state’s voter tracking website to ensure their vote is counted.

[...]

Mr. Padilla said [...] the boxes “are not permitted by state law.”

[...]

Hector Barajas, a spokesman for the California Republican Party, said the party would continue to distribute the boxes, without adding any label identifying them explicitly as Republican ballot drops.

Mr. Barajas — who disclosed that Republicans were responsible for the boxes only after being bombarded by questions by reporters on Monday — said the party’s actions were legal because state law did not restrict “ballot harvesting,” a practice that allows a third party to collect voters’ completed ballots.

[...]

“There is nothing in any of the laws or regulations cited in that advisory that indicate private organization drop boxes are not permitted,” said Mr. Barajas.

  NYT

Private organization drop boxes labeled "official"?

I don't know the letter of the law on that, but a lawsuit will surely follow contending that when you give your ballot to a "harvester", they're not claiming to be "official", and you at least have the opportunity to know whether they're trustworthy and will deliver your ballot properly and timely.

Republican officials purchased about 100 of the boxes in recent weeks in an attempt to boost turnout, especially in competitive down-ballot races, as party leaders fret about Mr. Trump’s drag on other Republicans, an operative with direct knowledge of the effort said.

They had installed about half of them by the time Mr. Padilla and other state officials took notice over the weekend.

State officials quickly ordered an investigation into the boxes, and Mr. Padilla sent a memo to county elections officials urging them to investigate the unauthorized boxes in order to “guarantee the security and chain of custody of vote-by-mail” ballots placed in them.

In his memo, he reminded local officials that creating an illegal polling site was a felony punishable by up to four years in prison.

...but hey, do what you want...you will anyway.