The problem of the deal wasn't the mechanics, it was how it was sold to the public. A competition putting cities against cities, negotiated without any public input, a large tax break to one of the richest companies in the world, choosing already popular cities rather than really investing in a newer one. Amazon could have definitely closed this deal if they pitched it properly.
70% of local residents approved of the deal. that is a lot.
Depending on
* how the question was framed ("Do you think the second headquarters of Amazon will be a positive?" vs. "Do you think the deal with Amazon will be positive?" vs. "Do you think tax breaks for Amazon are good?")
* how informed the voter was required to be; people are notoriously uninformed and uninterested about anything that isn't a presidential election
* how residents were contacted (was it a landline poll? mail? survey on the street? online? because these all have different populations to be accounted for)
* who counts as a valid resident for the survey? someone who lives in Buffalo? someone who lives in Westchester? someone who lives in Manhattan? someone who lives in Flushing? etc.
Polls predicted that AOC would lose her race, and that clearly didn't happen.