Testcontainers is awesome and all the hate it gets here is undeserved.
Custom shell scripts definitely can't compete.
For example one feature those don't have is "Ryuk": A container that testcontainers starts which monitors the lifetime of the parent application and stops all containers when the parent process exits.
It allows the application to define dependencies for development, testing, CI itself without needing to run some command to bring up docker compose beforehand manually.
One cool usecase for us is also having a ephemeral database container that is started in a Gradle build to generate jOOQ code from tables defined in a Liquibase schema.
