The reason why the conda env commands are not similarly documented is historical.

Namely, after conda was developed, others then developed an add-on package called conda-env that provided some convenience methods for operating on whole environments rather than package operations within environments. Eventually, the conda-env package was integrated directly into the conda package, but apparently there was never any systematic effort to unify the documentation. Instead, most of the high-level documentation on using conda env commands is found under the "Managing environments" section of the Conda documentation.

As an end user, I typically use conda env for creating (from YAML), archiving/serializing (to YAML), and deleting whole environments.

More directly, the documentation for conda env is consulted with

$ conda env --help
usage: conda-env [-h] {create,export,list,remove,update,config} ...

positional arguments:
  {create,export,list,remove,update,config}
    create              Create an environment based on an environment file
    export              Export a given environment
    list                List the Conda environments
    remove              Remove an environment
    update              Update the current environment based on environment file
    config              Configure a conda environment

optional arguments:
  -h, --help            Show this help message and exit.

and documentation of individual subcommands can be similarly consulted with conda env <subcommand> --help.