In the developing world, this is often the only link people have to the Internet at large. I worked in a company with primarily Nigerians and one of the biggest developments in recent years are payment systems built over mobile networks.
Since most other countries don't bundle the phone with a contract and SIM-lock them, SIM-swapping is a very reasonable way to pay-as-you-go while hopping between mobile networks and regions.
>However it is silly to pretend mobile is as safe as landline for all uses
What's the alternative for people lacking wired infrastructure? It's not desktop systems, it's not landlines, and they can't rely on the government to solve these problems for them.