[mhaymo]

This is a common sentiment, but seems wrong to me. It doesn't take a genius to recognise a spam or phishing email either, and yet no company has created a perfect email filter.

It's not neglect, it's a very hard problem, as is any problem where you are trying to make an inference with limited information controlled by an adversary. Amazon could spend billions on incredibly sophisticated fake-review-detection algorithms, but they still couldn't stop sellers finding real amazon customers and paying them to buy and review their products.

[schredder]

Neither the sentiment nor the difficulty of the problem matters. Big A gets a cut of a sale whether or not the reviews or products are genuine so they won’t do more than the bare minimum to deal with it, until their tide starts to change.