The full coverage explains that. This is a handicap series, where professional drivers and faster cars compete against amateurs and slower cars.

As a professional driver in clearly the fastest car in the field, Jono Lester was awarded a whopping 57 second pit stop.

He might even have still managed to win, except that there was a safety car just as the pit window opened and although some cars pitted straight away he didn't.

It was still fairly close

One other thing to point out is that the series format did help with the overtaking, since some of the drivers weren't used to such long races on a street circuit and would have been getting tired at the end (and therefore didn't put up much of a fight).