They didn't even agree with the 700 out of 1000 trips needing review figure

> According to The Information, 700 out of 1,000 Just Walk Out sales required human reviewers as of 2022. This widely missed Amazon’s internal goals of reaching less than 50 reviews per 1,000 sales. Amazon called this characterization inaccurate, and disputes how many purchases require reviews.

Even if the system was fairly accurate, if the vendor is charging Amazon too much for it, it can still be financially worthwhile for Amazon to switch to scanners in their carts.

"inaccurate" can mean lots of things here, from "actually it was 690 out of 1000" to some other minor technicality. Note that Amazon did not provide a figure of its own.

Large corporations tend to tell the truth, but push it as far as they can.

Might be "700 manual reviews per 1000 trips" getting misinterpreted as "700 out of 1000 trips needed manual reviews". If some trips were pathological edge cases that required near-constant reviews and a substantial majority took zero reviews, I could understand why Amazon would keep trying to fix its system.