Honestly I see a lot of construction workers using pneumatic or power nailers and I'm sure it saves them a lot of time. That said, I think I'm more comfortable with everyone taking a break at the construction site when the power goes out than with doctors being unable to treat people whenever a disaster affects their delicate electronic equipment.
To add to that, those are tools optimised for specific tasks, with an up-front cost that only becomes worth it if said task starts to become a significant part of the job. And with those tasks, they do so much of the work that you could almost say that humans only happen to wield them (I mean, I'm oversimplifying but it's kind of a matter of aiming and pushing a button).
Meanwhile, hammers, even in their various shapes and sizes, are more general purpose tools that "enhance" the skills and abilities of the human that wields it. Knowing how to use it also requires knowledge of the material you are working with.
Similarly, I'd say that stethoscopes are a general enhancement of a human sense (hearing), whereas other imaging techniques mentioned are more expensive, time-consuming, and specialised.
A skilled carpenter can work very fast with a hammer, sinking nails with one blow. But an unskilled laborer can work just as fast if they use a nailer. So I'd guess it's more about saving money than time.
https://en.wikipedia.org/wiki/Hammer