The New Math...

So I'm watching the news and they are interviewing passengers of the new shuttle that replaced the trains during construction.  One lady said she was extremely grateful that the shuttles will be free and that it will save her $300 a month in travel expenses.  Really?  I know I'm a bit rusty when it comes to my math skills but the cost of a 30 day pass is $100 dollars.  This gives you unlimited rides for a full 30 days.  I know the cost of riding can skyrocket if you are paying daily but if you know that you have to ride that often then why not just buy the pass?  I know of people that buy the 7 day passes every week and never think of how much money they can save getting the 30 day.  These are the same people that swear that they will never use math in the real world.