Most have access to one, in the developed world.

So there's the option, but it's a service change for many. Which is an argument against your comment.

If you're taking the broader view -- outside developed countries, or to a time when POTS / PSTN are deprecated or abandoned, and I could see that happening within the next five years given recent trends, possibly not. Which is an argument for your comment.

My experience is that both landline and mobile have their own extreme annoyance and distraction factors. So be it.

Outright dismissal may be not fully appropriate and premature though.

Though again, that's households without landline service. The households still have landline access, in the sense that they're wired to the network.

The actual penetration is closer to 20% now in many regions. Staggeringly low. And again, I think PSDN as a whole -- that's mobile dialed and VOIP SIP calls, as well as POTS -- may not be long for this world. The spam / robocall issue is the tip of the iceberg. Personal and business fraud is another major element.

For median household income it would cost 1.5% of after tax income for just the landline

In ancient times, the frequently-called numbers list was pinned next to the phone.