My $20 "Pittsburgh" calipers from Harbor Freight (don't judge) are still on their original batteries, after 6 years. They have a power button, and a separate zero button.

They don't actually turn off though. It just turns the display off. They need to continuously sense position since digital calipers measure movement increments rather than absolute position. That's why if you take the battery out and put it back in it will prompt you to re-zero the calipers.

Amusing video explanation: https://www.youtube.com/watch?v=KnDype-j3hk

It's not uncommon for them to be designed to require zeroing at each power on.

Many of these “auto zero” which is why you have to do the scale dance - tap it with your foot to turn it on, wait for it to say zero, then step on.

Yeah, my explicit mention of kitchen scales and calipers was intentional, they both become much more useful if the user can choose to zero the readout at any time.

This is less true for a bathroom scale.

Went not just stand on it while it tares and ignore the negative when you step off?

All the digital bathroom scales that I've encountered refuse to display negative measurements.

Well my kitchen scale does. Though I don't know many people who weigh less than five pounds.