This isn't limited to Amazon. Stuff like this has been going on forever, even before the internet took off. For example, most trade services in real life will

This isn't limited to Amazon. Stuff like this has been going on forever, even before the internet took off. For example, most trade services in real life will offer you a gift in return for a referral. A referral is in my opinion a lot stronger than a review because now you're personally vouching for something to a friend or family member. Amazon reviews are basically a distributed version of that with less individual weight, but effective in the end due to volume. I would never in a million years ever leave a positive review in return for a gift, but if there's a service that I enjoy using and really believe in it, I'll happily refer it to friend with or without compensation and if the company wants to compensate me, I'll accept it. Like a dentist giving you movie tickets or DigitalOcean giving you hosting credits, etc.. It's a fine line tho because that referral logic doesn't apply back to leaving reviews. It's an interesting topic because so much of it is based on "feel" rather than black and white rules.