The National Safety Council’s definition of a preventable accident is: An accident in which the driver failed to do everything reasonable to prevent it. Defensive driving means “driving to prevent accidents in spite of the incorrect actions of others, and in spite of the adverse conditions.

Some accidents get logged as “non-preventable” when they are clearly preventable.

The usual mistake seems to be in assigning “fault” rather than preventability.

A driver can be technically free from fault, yet may have been able to avoid the accident. Unless you are driving defensively (to prevent being involved), it may be only a matter of time before you are involved in an accident.
Are “right turn squeeze” accidents preventable? Usually they are. Block off that right lane and pull forward a little farther to complete your turn, after traffic clears. Practice those turns correctly instead of just “getting around the turn”.

Slow down in adverse conditions (i.e. weather, road, light, vehicles, obstructions).

Slowing down allows for much shorter stopping distance. It also allows you much more time to see everything and to make correct decisions. Keep as much space as possible between your vehicle and others.

Do not assume “right of way”; the other vehicle may not yield.

Merge at on-ramps; do not force your way into traffic. Likewise, when someone is trying to merge, slow down and let them in because they might not merge correctly.
And that might involve you in an accident that you can usually avoid.