There is nothing to compare the idea to here in the United States except maybe a strip club that serves pizza, but that's not really the premise of the Pizza Express plan. Pizza Express locations are located in upscale neighborhoods in and around London where they are well known for their unconventional marketing. The new flirtatious plan is hoped to redefine the restaurant experience for customers and promote an atmosphere more conducive to conversation.
Beyond simply encouraging employees to flirt, U.K. newspapers report the chain has even gone so far as to hire a trained actor to teach flirting and the art of small talk to them. A company source was reported saying "With social media and texting reducing our face-to-face interaction, Pizza Express has enlisted the help of a conversational expert who is incorporating flirting and unique conversation techniques. We're experimenting with just about everything, from design and acoustics to service and food."
The expectation is obviously that happy customers will spend more money. If they feel chummy with the restaurant staff maybe they'll stay longer and return more frequently as well. However, applying the Pizza Express model here in the U.S. could be a bit more problematic when one considers the litigious nature of American society. In this country the plan brings to mind images of over-enthusiastic customers getting their faces slapped by not-so-enthusiastic servers. So far, reaction in the U.K. has been mostly a wait and see attitude with some commenting that unless the amorous acting is really very good, it could backfire when customers realize the employees are only being nice to earn more money.