As it happens, the numbers in bitcoin are so large that it doesn't matter too much. As you can read above, if every person on the planet generated 77 thousand addresses every second of their life for the next 75 years we would expect a 50% chance of collision.
To be honest, I don't really think that's enough of a margin if we're planning to be secure for a long long time, I would rather see orders of magnitude similar to the age of the universe. However, it's certainly enough for our practical purposes today. Possibly by the time it becomes relevant, bitcoin will have evolved to use a different addressing scheme.
When your team of 6 billion finally finds a collision on average you'll get 21 million bitcoins / total number of addresses. That'll be exciting.
I'll keep my wishes for safe car rides.