Lets do some basic math. Lets say you pay a driver $10/hr to drive 8 hrs a day at an average speed of 35mph in the city. That is about 250 miles covered per driver, per day and $80. So you do that for 10 days and that is 2,500 miles for $800.
Now you build 10,000 cars with street view like capabilities, call it $40,000 per car, perhaps you get a car maker to help you perhaps not. that is 400M$ for cars, and 10,000 drivers is $8M for 10 days and 250 million miles. You haven't even spent close to a billion dollars and you've got street view like imagery for every major city on the planet in 10 days. Run this program for a year and you cover every road twice with your 10,000 drivers.
Its certainly doable by Apple if they choose to go that route.