We eat at Indian restaurants, so we would probably try an Indian meal prep service. It's not familiarity, per se - or it is just to the extent that we need to believe it'll be tasty. (Trying a new service involves a certain amount of in-the-moment impulsiveness. Like, "Mmm, that sounds good...")
A good price on a flier will usually get us to give it a try. (The rationale is "that's about what we pay for a meal now anyways" or "that's cheaper than a restaurant." Or, "it's probably healthier than what we're eating now.")
The bigger question is why do we stop using the services. That's usually "I didn't really like the taste of the last couple meals" or "I'm getting tired of the same limited choices." At some point you recalculate the per meal cost, and decide it's not worth it.