Unfortunately Amazon does not. I recently got in an argument with someone who (IMO) gave out 4/5 star reviews. The reviewer countered that no, she had given out 1 star reviews. She had reviewed hundreds of items, and Amazon's lame interface displays 10 reviews at a time, with no ability to sort by number of stars (or other useful filters). I finally found her 1-star review of a self-published e-book, but by that time didn't have the energy to pursue it further.
A histogram of reviews by star would be extremely useful. Obviously Amazon doesn't care about the consumer's ability to rate the reviews, though, given how little thought they've put into it.
Elsewhere I posted about bogus five-star reviews. I suspect publishers simply hand out money to shills to create bogus Amazon accounts and post 5-star reviews of their books that suck. I'm not why so many here think that limiting reviews to purchasers would solve things. Also, I always read books at libraries before I buy them. So, you'd cut down on the number of negative reviews from people like me.