The approach they show in the end - it's still machine learning though? Exploring a space and finding parameters to optimize for a loss function (speed around the track), just not deep learning with neural nets.
It might not be a hard boundary, but I think the perception of ML vs. optimization is how much of a model you have. If all you have is a black box, then it's ML; if you know how the system you are studying works, it's (parameter) optimization.
But machine learning has predated neural networks by hundreds of years. The core mathematical basis of all machine learning coursework linear regression and decision trees. Other models like SVMs, Bayesian models, nearest neighbor indexes, TFIDF text search, naive Bayes classifier, etc., are basically like machine learning 101, and they have many different properties regarding interpretability depending on the problem to solve.