And the machine results were audited by a hand count, in some cases a full hand count (e.g. Georgia), and shown to be accurate.
Witness all the fireworks that suddenly explode onto the scene when signature validation comes up.
Case in point - Gavin Newsom suddenly got really concerned about signature validation - but only for his recall election :p
The absentee ballot envelope signatures in Georgia were hand-validated by staff. The results were then audited by another hand validation by different staff later and found correct. https://www.thegeorgiasun.com/2020/12/29/georgias-signature-...
Regarding signature validation on ballot petitions, that’s a normal part of petitioning. The process for gathering petition signatures is very different from absentee ballots and usually results in the collection of a lot of invalid signatures in every political cycle (either real people who signed but accidentally broke some obscure rule, signed multiple petitions, etc, or just fraud on the part of the paid petitioners who are paid based on the number of signatures they gather).
One of the funniest things I heard in awhile is when Kreb's said the election was the 'most secure history'