It is not decision tree or any machine learning algorithm. It is a local search algorithm that probably has simulated annealing or tabu search as a metaheurist

It is not decision tree or any machine learning algorithm. It is a local search algorithm that probably has simulated annealing or tabu search as a metaheuristic. Although, they probably segment the deliveries to some common starting points and the problem size is reduced significantly - maybe to around thousand orders per starting point. Research can easily optimize thousands of deliveries very effectively.