Hi Doug,
The Guardian's API doesn't actually exist any more, if you try any of
the links from the page you quote. So that's one thing, in that we can
manage to maintain and keep things running for approximately twice as
long as a national newspaper ;-)
As I understand it, the conditions are the result of being a project
of a registered charity; we can only freely support other charitable
projects, and must charge for anything more. We define charitable
usage on the API page as "direct use by registered charities, or
individuals pursuing a non-profit project on an unpaid basis, with a
volume of up to 50,000 calls per year." – if the advertising you
mention is to cover hosting costs, as you say, then that seems to me
to be a non-profit project. The volume limit is because we do have
costs associated with maintaining and supporting the service (Hansard
still requires frequent manual fixing to process, for example). The
police/government might have slightly more budget than us :-) But if
their APIs meet your requirements, great.
ATB,
Matthew, mySociety