How accurate are claims that the US election is rigged?

The election is rigged because many postal ballots are not counted

Question: How accurate are claims that the US election is rigged?
Position1 of 3›: Claims that the US election is rigged are very accurate
Argument‹6 of 6: The election is rigged because many postal ballots are not counted

Claims that the US election is rigged are very accurate. Many postal ballots are not even counted as the election is rigged.

The argument

In September 2020, Facebook photographs of "dumped" ballot envelopes in California were shared thousands of time on social media with claims of election rigging.

Premises

[P1]Photographs circulated on social media in September 2020 showed discarded postal ballot envelopes in California. [P2] Discarded ballot envelopes indicate that legitimate postal votes are not being counted. [C] Therefore, the US election is rigged because many postal ballots go uncounted.

Counter-arguments

The official County of Sonoma published a statement addressing the postal ballot fraud claims: "The pictures are of old empty envelopes from the November 2018 election that were disposed of as allowed by law." In fact, the county's ballots for the 2020 presidential election had not even been sent out to voters when the pictures claiming rigging where shared.

Rejecting the premises

[Rejecting P1] The photographs do not show what the premise says they show. The county identified them as empty envelopes from the 2018 election, disposed of as the law allows, and ballots for the 2020 election had not yet been sent to voters when the images circulated. [Rejecting P2] Even had the envelopes been current, an empty envelope is the container a voter opens and throws away, not an uncounted vote. A discarded envelope establishes nothing about whether any ballot inside it was counted.