It may also signal uncertainty when two green light products are available at the same point of purchase. The only way to recommend one is to know the price premium the consumer is willing to pay, which will require translating the score into currency, so that a device or him/herself can calculate whether the price plus the premium they find to reflect its merits, is more favourable to one product or the other. With all this information in the database, the yellow light could simply be a price, meaning buy at this price. The acceptable product which comes closest to the buy price is the one that the consumer should buy.
Possibly in this instance, however, the end user will want to review the detailed comments about the product looked up by barcode. There may be good reasons not to use the same criteria to evaluate both of the products. Comments are a note in Simple English about issues with, and merits of, the product. Probably filtered from opinion wiki.
Hardware requirements to make this easy at point of purchase are severe. It may be these requirements that kill the project! So coordinating with other essential projects is quite important. One of those other projects may actually help justify the hardware.