There's a second dimension, cost. Google is essentially in the same business as the ancient yellow pages directories, just almost infinitely more automated and cheap. Those predecessors didn't just select a different trade-off, they had high quality vetting baked into their expensive manual process without even trying. But the customer who could in theory choose between the cheap and the vetting isn't the victim of substandard vetting, so there is no market mechanism to slow that race to the bottom.