How common are core routers in the ISP environment?

I started working at a smaller ISP half a year ago and was a bit shocked to find out that almost everything is essentially layer 2. The only routers I've come across so far are edge routers. Is this common practice?

We essentially have like 2 big erps rings that all have their own edge routers that go back to the location where we peer with AT&T and other backbone providers.