Public transport gives flexibility for both of you - do you seriously want to spend half your day driving back and forth between Brentwood and Southend? Unless you work here, of course? Having a season ticket means that your DD can travel at any time, over any part of the route, making it so much easier to meet up with friends at the weekend / in the holidays without having to rely on a parent taxi service. Or even hang out / do homework upstairs in Utopia after school as an alternative to the library - much better cakes, even if there are cupcakes at SHSG today for the school's 101st birthday
Two of ours travel on c2c, albeit only 3 stops to Southend East; DD knows girls coming from at least as far up the line as Barking and she has a friend using the other route who lives in Shenfield who was quite happy to just hop on the train one Sunday recently to join DD's birthday lunch party at a restaurant in Southend.
And yes, you will be bowled over by the number of pupils using the various routes