This is about making the same files accessible inside and outside a container. Docker does that by bind mounting files from outside of the container's file tree into it. Bind mounts are just a way to provide a different file path to access an existing directory. It has zero performance cost.
The reason Docker Desktop and similar solutions need to come up with these different complicated solutions is that they want to share files between containers running inside a Linux VM and the host system. So they need some kind of way of syncing the files.
The reason Docker Desktop and similar solutions need to come up with these different complicated solutions is that they want to share files between containers running inside a Linux VM and the host system. So they need some kind of way of syncing the files.