It is not problem only on amazon but pretty much on any big platform where bying comments gives you an advantage
It is not even the real problem, it is just a simptom.
The root cause is that people still have to compete for their livelihood, and cheating is always a viable way for some.
Our thinking and the world will have to evolve past the current state of scarcity.
Then nobody will be incentivized to waste their intellect on covertly conning people for financial gain.
Given that, culture is really the solution to problems of cheating. Which, of course, is not a technical solution either.
I bought a vaccuum recently and did this process. One of the 1 star reviews was something to the effect of, "this vacuum sucks too hard. Its a workout to use". I have 2 huskies and a sea of fur to contend with, so this 1 star was a 5 star to me.
I think the best way to improve things is via increased transparency - If I can read a reviewer's past reviews, I can make a better-informed judgement of their reviewing integrity.
The reputation of a reviewer needs to be on the line to get proper reviews, and also the ones reading the reviews need to have a way to gauge the reviewer's reputation.
Knowing someone in real life helps, but so could something where we can review the reviewer.
The first and biggest one (in my opinion) is global unique item identifiers for the products. This reduces the sheer ridiculous volume of reviews you have to contend with. The other problem this solves is that the "review" is now reasonably guaranteed to be attached to a product and not "seller plus product". This leaves very little wiggle room and incentive for dollar-store / drop-shipper / chinese knockoff sellers to fake reviews.