The text discusses the importance of implementing zero-trust security in modern applications, particularly in microservices architectures, by drawing an analogy with passport checks at airports to highlight the need for identity verification. Zero-trust security is crucial as it eliminates the reliance on trust, which can be exploited, especially when dealing with numerous services in a microservice setup. The text emphasizes using service meshes, such as Kuma or Kong Mesh, to enforce zero-trust security by providing virtual "passports" or identities for services, thus ensuring secure communication through mutual TLS and traffic permissions. It describes how service meshes simplify the process by automating the creation and management of certificates and identities, allowing application teams to focus on development while infrastructure architects handle security. Kuma, an open-source service mesh, is highlighted for its ability to enforce zero-trust security across different environments by automatically connecting services and rotating certificates, thus providing a secure and scalable solution for microservice architectures.