DS needs his phone to zap on and off the bus. The days of 30p for the bus fare are long gone.
Around Christmas there was a storm and the bus service and route was heavily affected by fallen trees, including one stretch of road causing a lengthy diversion through a labyrnithe housing estate. It took him 90 minutes to travel the 3 miles home. While arguably walking would be far quicker in those circumstances, that was not a safe option in those conditions, and the only way he knows to avoid that closed section on foot would be off-road at very high risk of trees falling with no help nearby. He was safer staying at the bus shelter and on the bus.
There is a grand total of zero pay phones on the journey home. The pub halfway is not the kind of place where an autistic 12 year old will be able or allowed to walk up to the bar. Reciting my phone number backwards 3x can not summon me.
Smart phones allowed him to check the bus website for information, contact me to keep us both updated and reassured (because it's natural to be concerned about an otherwise missing 12 year old at twighlight in a storm even without the added complication of autism involved) and use google maps to know where he was in unknown areas.
It wasn't practical for me to go and rescue him because I'd be subject to the same traffic chaos. Plus I was waiting at the bus stop for him as the walk home isn't great at twighlight anyway, so I was able to update him on where I was waiting safely. I didn't have access to my car.
The phone was a vital tool and saved a huge amount of worry on both sides, and gave DS the information he needed to cope with a stressful situation and avoid shutdown or meltdown. It meant I already knew that bus#1 had been too full to pick up at DS's bus stop and he was still waiting rather than being concerned about him not getting off.
In contrast, DS2 doesn't need a phone for a simple 300m walk from primary school, although now on the cusp of leaving, he can use it to update me on spontaneous plans on going to play with friends.
I have no issue with phones being off or shut away in school, but they are necessary for many pupils' journeys.
The days of payphones and bus passes on cards are long over and young people learning to be independent need to learn to function in their current world not a rose-tinted 20th Century version.