The other$-$than$-$collision coverage of a personal auto policy does not cover most losses caused by a collision because

a$.$ an insurer can collect more premium by having separate insuring agreements for different perils.

b$.$ collision coverage costs less than other$-$than$-$collision coverage.

c$.$ collision losses should be covered under the policy's collision coverage, if that coverage applies.

d$.$ people would otherwise assume that the policy was comprehensive and had no exclusions.