Do people in other parts
of the world have access (both physical and logical) to enough
bilateral peering (and budgets...) that it makes sense to deploy
a router per peer?
Certainly not a router per peer, but a peering router per city,
where it may connect to one or more exchange points. This is what we
do.
Granted, it does increase your budgeting complexity, but in our
case, over time, the delineation has actually simplified operations
that the architecture has paid itself back many times over.
In the real world, this is not always possible, and I understand
that a peering router for some networks may also be providing
transit as well as edge functions. This is quite normal, even though
it can create other complexities depending on whom the eBGP session
is with - which then lends itself to running parts or all of the
Internet in VRF's and all that hocus pocus. When we tried this sort
of thing at a previous job some 14 years ago, it was just simpler to
have separate routers each handling transit, peering and customer
edge.