The amount doesn't really matter. What matters is the variance. There could be only 3 radiologists in the world that use different practices with 1% 10% and 50% error rates. It would be misleading to say "Radiologists miss 50% of diagnoses" based on one practice.

The assumption when gathering these statistics is that more or less you can average these out, but with AI you might have a model with literal 100% error rate or a model with a much lower error rate, and that changes a lot depending on the AI method its using.