Given that countries like the UK use roundabouts incredibly extensively, and they have never been shown to be a cause of increased accident rates, I suspect that your suspicion about this is probably wrong.
It depends on the country. Familiarity with roundabouts would be a necessity in the UK. In parts of the world where roundabouts are only recent, there are many drivers who are too old to “learn new tricks”.
I’ve got older family members that have self-excluded from driving to the provincial capital because the roundabouts are overwhelming.
I have older friends who self-exclude from driving at night. That doesn't make me conclude that night-time driving is inherently a problem (even though it is, based on statistics, more dangerous than driving around a roundabout).
I’ve got older family members that have self-excluded from driving to the provincial capital because the roundabouts are overwhelming.