Montreux-Caux line is marked as usage=tourism, but AFIAK it is very extensively used by residents of Glion & Caux, and by students at the hotel school (https://en.wikipedia.org/wiki/Swiss_Hotel_Management_School). In the Winter most trains just run to Caux, with trains to Rochers de Naye only at weekends. The Caux trains also run well into the evening: a good indication that it is not solely for tourists.