Is it just the last mile that makes cable/dsl broadband not suitable for enterprise?

We have observed much higher latency loss and jitter on broadband connectivity cable/dsl than we have with DIA Fiber/Ethernet handoff.

Is that just caused by the nature of the last mile? Or is something else at play? For example, how is latency so much higher. We had a circuit that was measuring about 110ms latency that’s now 20-30ms on Fiber. How can such a thing be?