Exactly. I always think about the ways consumers make terrible decisions with everyday purchases at the grocery store etc. If people could easily estimate unit costs in their head for example, a lot of predatory options would have to go away. But calculators keep people from having to get good with everyday math in their head, while those same calculators sit unused in many everyday scenarios where people don't go to the effort to use them.

Quick estimating (which is a different skill from calculating exact answers using pen and paper) is most useful there. People do carry computers with them these days and they do have calculator apps. Some shops I buy from do have unit prices for many items.

I think AI might be more of a problem, at least for some skills because it is not just doing a small unit of work. its more like the problem of doing more complex calculations. An example I have come across with calculators is students learning statistics without knowing how to calculate a variance, because they just put the numbers into a calculator. There is a failure there to learn the concept - they do not really know what a variance or SD is. I can imagine AI doing a lot of that.