Why does the raster type not have send/receive defined?

Hello,

I haven't used this mailing list before and couldn't figure out how to
search in the archives, so I apologize if this has been answered before.

Is there any specific reason why the raster type does not have the
send/receive functions in its SQL type definition?
The geometry type has these defined as conversions to/from EWKB, which
are equivalent to ST_AsEWKB/ST_GeomFromEWKB if I understand correctly.
Equivalent (E?)WKB conversion functions exist for rasters in the form of
(RT_)ST_AsBinary/ST_RastFromWKB, but have to be called explicitly.
I would like to use PostgreSQL features like COPY ... WITH BINARY with
rasters, but it seems this is preventing me from doing so.

Sincerely,

Lukas