https://www.hexmarksthespot.com/school-pickups/

We require a minimum of 3 children from each school for the day in order to provide school pick-up.

If fewer than 3 children are registered for pick-up from a particular school on a given day, families may still use the service by covering the cost equivalent to 3 children for that school pick-up.

For example, if only one child needs pick-up from a particular school, the family would pay the cost of 3 school pick-ups for that day. Two families may also split the cost of a third child for pick-up.