Engineers aren't miracle workers, granted. Which is why it is their responsibility to thoroughly test the devices they design and document their limitations. It's then on the medical industry to train doctors and nurses on those limitations.

I’m sure pulse oximeters now are more accurate than they were 20 years ago.

As I said, this continues to be a problem into the present day. COVID-19 patients with dark skin would suffer from hypoxia that pulse oximeters would fail to detect, leading the medical staff to fail to administer supplemental oxygen. That's probably happening somewhere on earth as I type this.

Do the little lights in the device need to be brighter, or have a brighter mode? Does their need to be a switch on the side? Can our cultures handle a medical device with a "white people | black people" switch on the side?