We don’t own a calculator either. One of the only reasons they’re still around is their simplicity, which is desirable in an educational setting. If it wasn’t for that, nobody[1] would use them any more. Excel and computer algebra systems are superior for all practical purposes.
[1] For some values of “nobody”. There’s always the elderly, purists, luddites, or just those slow to adopt.
There are other applications too, where the resistance of the bulb itself, and how it changes with the amount of current going thru the device is also important.
In a sense, the exception makes the rule: the fact that only niche applications remain reinforces the point that these are legacy technologies.
I know lots of legacy technologies that are far from even approaching obsolescence. I know many specialty technologies that used to be mainstream.
Thats sorta my point - like my industry uses 2w analog control loops with inband signaling - while this has been obsolete for new designs in most other industries, in mine its still current technology and continues to be used for new designs and implementations - if for no other reason than its a well understood easy to implement interface.
Calculators are still sold in many shops. I can literally cross the street and go buy one at the supermarket. It's not about being "slow to adopt": they're superior to using a computer's calculator or, even worse, a smartphone's calculator app. A smartphone has shitty input controls compared to a calculator and it's not "one button to press" to get it ready. First unlock the phone, then open the calculator, then use the shitty input method.
Also many calculators, since decades, are solar-powered. It makes lots of sense: you're not going to use them in the dark. And they use so little power that a tiny solar panel incorporated into the calculator is sufficient. No need for USB-C crap cables.
You know where you see a lot of these, next to computers, used by people spending their entire the day at the computer and with their phone in reach and used by people doing computation at all times? In accounting offices.
Accountants are neither luddites nor old nor purists nor slow adopters. It just happens that for some kind of computation, a pocket calculator is simply the very top of the chain.
The following picture shows what survival of the fittest looks like:
https://en.wikipedia.org/wiki/Calculator#/media/File:Casio_c...
There are even calculators to make construction estimation easier too.
Most people who are just using it as a tool to figure something really quickly have probably moved on to use something less specialized, like their smartphone.