~25 years isn't the average when you account for accidents, rust, and useful economic life of a car. We had 200+ car crashes due to weather in a single day this week in Waterloo, Ontario.
The average car in Canada is 10.5 years old, in a steady state you double that to 2 * 10.5 =21 years lifespan on average. However the country isn’t in a steady state in 2005 there where 33.5 million people in Canada in 2025 that hit 41.5 million.
So because the number of new cars purchased each year is increasing the average age is significantly below 1/2 the average car’s lifespan.
The average car in the us is 12 years old, so expected life of 25 seems reasonable. Not all make it that long but many will