If people want to buy $5 “scientific calculator”, a 4-function calculator with a paper tape, use a free calculator app on their phone, type their arithmetic into google, ...., that’s just fine.
These devices are simple and straight-forward, and do not need extensive practice to understand.
If schools really want to spend class time practicing computations with a portable calculation device, learning how a slide rule works is much more pedagogically valuable. At earlier ages, learning how to use a soroban or counting board is also worthwhile. These devices have no hidden parts, and learning to use them is, in itself, mathematical.
You on the other hand called _all_ handheld calculators a waste of time.
Spending nontrivial amounts of classroom time on practicing using a handheld calculator is a waste. Assigning high school students long lists of exercises where they punch numbers into calculators and then write down the answers is a waste of time and attention.
> Learning to fluently navigate a handheld calculator is not an important life skill
It very arguably is. Contrary to what HNers seem to think, not everybody wants or is inclined to picking up Python to tally up a receipt or similar, and that's quite okay. (Sure, the handheld calculator is often now a phone, but that's a difference without much distinction)