Querida,
Good question.  Just another example of how we in the US assume the rest
of the world is familiar with what we do...
About the ped visits, actually, yes, they are in effect mandated.  Most
(if not all) states have laws requiring children be vaccinated prior to
entering the public school system around 5 or 6 years of age (religious
exemptions are permitted).  The goal of pediatricians is the have the
vaccines given on a specified schedule, beginning at birth.  As any of
the pediatricians, family practitioners, family nurse practioners, etc.
on the list who practice in the US can tell you, we are nowhere near that
goal.  Because the babies are brought back for these vaccines over the
first several months and years, weight checks are usually done.  The
normal healthcare provider for children is the pediatrician, although
family practitioners, nurse practitioners and physician assistants are
sometimes seen.  It also depends on where in the US someone lives, for
which healthcare provider may be more available.
The other reason I think there is so much ped intervention and reliance
by parents is that new parents are not made to feel confident in their
knowledge base about their kids, and the appropriate choices to make for
them.  I'm not sure if this is only in the US, or elsewhere.  The joke I
hear time and again is that if all babies were second babies, there would
be no need for pediatricians.  Of course that isn't really true, as kids
will forever be getting sick and we need the medical help.  However,
maybe parents wouldn't be calling the peds (and others) so much for
things they should be researching for themselves and making parenting
decisions, not medical decisions.
Seems I've gotten off topic a bit, but I think I made the point...
Lee-Ann Halbert, RN, IBCLC
in New Jersey (east coast US)