The depressing thing about the Amsterdam scenario is that you're in an awkward position of being a good human and helping, vs weighing up the risk of being scammed and ending up as a victim of crime.
A lot of people are wary of teenagers anyway so may be reluctant to assist.
I don't want to put my teenagers in a position of having to rely on good will from the public when there is a simple self-sufficient solution that covers most likely problems occurring. Their walking route is safe, but not heavily used by pedestrians and is not great for opportunities to ask for help. A lot of it is industrial, then they end up in countryside.
They know the back-up route for walking, that covers phone-related glitches/ catching the bus, but with incidents like the fallen trees in the storm and the knee injury it was best that they had the smart phone avaliable to aid with locations and support.
There are people who seem to be expecting more independence skill from a teenager than of a significant proportion of adults who'd do that journey with their car and smartphone.
Fortunately I'm happy with my DCs' school policy of phones beyond use in pouches in the school day when they're not needed, and not policing their access to devices for commuting safely when off the school grounds.