Let's say each ride cost $10... that is $20 to $40 per day just for the kids on most weekdays. Add in birthday parties, saturday games, doctor/dentist, trip to grandma/grandpa that live 7 miles away... and we are talking $1000 per month in "ride-sharing costs" for my children alone. We could add in my wife and I's costs, but it would be silly.
Maybe this service is less than $10 per ride, even at $5 per ride it is wayyyyyy more expensive than I currently spend on a 4 year old Toyota Highlander with low miles with insurance and fuel.