Do you have any idea how people get reviews to show up on their products in Google Shopping?
Yes, there are two different services that are typically used to created these reviews:
Bazaar Voice is used to create reviews on individual products in your catalog, and that's why you see them listed underneath the product in Google.
Shopper Approved creates reviews for your store, and that's why you don't see them listed underneath the products. Shopper Approved reviews also show up next to your Google AdWords ads in the Google search results.
Bazaar Voice is a fairly expensive service that's used by many of the bigger retailers. Shopper Approved is a lot more affordable and will fit into most retailer's budgets.
Please submit a Support Request if you'd like Modern Retail to help you implement either of these reviews. Thank you.