> If someone is willing to focus on organizing this effort, it might do
> some good.  One very good step would be to convince GitHub to identify
> packages with the modern SPDX identifiers.

GitHub does already try to recognize the license used by a repository
using heuristics. These can be programmatically fetched:

    $ curl --silent -H 'Accept: application/vnd.github.v3+json' \
        https://api.github.com/repos/melpa/melpa/license | grep spdx
    "spdx_id": "GPL-3.0",

Repeating this process for some packages mentioned previously in this
discussion (the 0x0 one has been omitted as it's hosted on sr.ht):

    $ curl --silent -H 'Accept: application/vnd.github.v3+json' \
        https://api.github.com/repos/davidshepherd7/aggressive-fill-paragraph-mode/license | grep spdx              
    "spdx_id": "GPL-3.0",
    $ curl --silent -H 'Accept: application/vnd.github.v3+json' \
        https://api.github.com/repos/alan-platform/AlanForEmacs/license | grep spdx 
    "spdx_id": "MIT",
    $ curl --silent -H 'Accept: application/vnd.github.v3+json' \
        https://api.github.com/repos/rolandwalker/anaphora/license | grep spdx
    $ curl --silent -H 'Accept: application/vnd.github.v3+json' \
        https://api.github.com/repos/davidshepherd7/anki-mode/license | grep spdx
    "spdx_id": "AGPL-3.0",

That gives me a more precise picture than Jean Louis' analysis I've
taken these packages from. The only license that couldn't be identified
is for the anaphora repository which doesn't have a LICENSE file, but
instead embeds a public domain notice inside the source code.