They’re giving 0% interest, which is a discount. It’s rational to take that instead of paying cash.
It's been normal(ish) in cellphones for decades now, at least in the US, to offer a payment plan for phones. It was tied to your plan, which is still how a lot of these work.
come on, vagueboy. what are these things?
That people can't even afford to save up the few hundred dollars to buy a phone outright.