It's like exposure, only even more insulting.
But first you're going to need a solid track record of legitimate-looking reviews (usually upwards of 50) attached to whatever social media account you're using, which must also carry a good number of followers. The reviews can't just all be five stars, or else Yelp or Google can tell you're a shill. In short, you need to build up some trust before you betray it for cash. On my two Yelp accounts and my Google account, I'd make sure there were a few hundred varied reviews visible on my profile at any given moment.
But you have to be careful: Yelp protects the identities of its reviewers to the steps of the state Supreme Court if need be, but Amazon will sue the pants off of users posting fake reviews. You basically have to do a few months' worth of unpaid work before you can even start looking for work, which is pretty much the case for all college graduates nowadays.
Only the truly battle-tested can handle the pressure of telling the world you liked the ravioli.