FWIW, telco companies in Mexico don't charge for WhatsApp data transfer. As for prices, a 30 day Telcel 4.5GB plan is 200 pesos ($10) per month. So long as you don't use up the data doing things outside of WhatsApp, like surfing the web, which will expire the plan, then you get free WhatsApp (and Instagram and most social media) transfer for the month.
So it's not the worst organic solution and it's not even obvious how to centralize a better solution. For example, how many subway drivers are there and how much govt bureaucracy would be needed to do something like give everyone a $10 stipend for WhatsApp? Even giving each driver an extra $10 pesos per month wouldn't change anything.
The radios of those are outside. The radios of subway are underground. It's not great for radios, requires infrastructure, and phones solve it in same way, by having infrastructure close to cover for reduced range.
Then you upgrade? There's nothing that precludes that the bespoke system won't die and by the looks of it the current system has already died leading to the use of Whatsapp.
it wouldn't be that expensive to make your own app that sends and receives messages over 4g.
Those people might be right. But I'd like to point to the old solution, the radios in the trains, which are in the middle of a decade long outage right now. It's more reliable than that.
And this stuff isn't safety critical - in-cab radios are mostly used for logistics. Everything from scheduling shifts to getting trains to wait a few extra minutes to even out gaps in the service. Without it, the service wouldn't run so smoothly. But it could still run.
> Previously, each train could automatically identify its proximity to another one. “It is designed to stop so trains don’t collide,” said Pérez Varela. Now, human operators, who had initially been hired as a fail-safe to manually halt a train if the automatic pilot failed, need to intervene more often. Trains usually run at 70 kilometers per hour, but when the autopilot signals that it is not working, operators must take immediate action to manually reduce the speed to 35 kilometers per hour to avoid derailment. > > Since the trains are increasingly manually driven, real-time communication among operators is essential. “We are all provided with a radio but it doesn’t work properly,” Jaime, an operator who has worked at the Metro for 17 years, told Rest of World on condition of anonymity. “That’s why we started using our cellphones.”
That reads to me like they need communication to ensure they don't run into the rear of the train ahead.
WhatsApp is consumer-grade software. Using it to manage a transport system is like using a $50 home-oriented manual espresso machine in a busy cafe instead of a proper commercial unit with automatic grinding, multiple nozzles, and a support agreement in place.
The reason its so good is how it handles edge cases. it brilliantly handles edge cases like when connection is extremely spotty. In 2015 when I was backpacking around Europe I learned this the hard way when iMessage repeatedly hit issues where it would get stuck transmitting mid message and would require drastic things like rebooting the iPhone (because that damn status bar gets stuck and then you have no recourse) whereas no matter how slow/spotty the connection (like 64kb/s or slower), Whatsapp would patiently work and reliably get the transmission through eventually.
In hindsight, I am thankful Zuckerberg had the sense to acquire them. He has so far done a lot less to destroy it than I expected. Can you imagine if they got acquired by some garbage dump of a company like Oracle, or Salesforce, or (shudders) Google? Just think of all the ways they would have ruined it.
The 'proper' solution of new radios on the train and all the associated ground infrastructure installation cost could be really expensive (think millions of dollars). Yet just giving each driver a data plan would only cost thousands of dollars.
The whatsapp solution is so much cheaper because the infrastructure (4G towers) is already installed for passengers of the train, the network is already run for citizens of the country, and the software work is already done by Whatsapp for their other 1.1 Billion users.
Whatsapp isn't a 'cheap' solution. It's the very expensive solution where the cost has already been paid for by a billion other people, so, as long as it meets the needs of the subway, it is the cheap solution.