15 y/o comes out with new cancer screening.

The drug companies will make it cost more just to cover the liability of the 10% it does not catch. 90% success means 10% of the users will sue you for missing their cancer. Tort is one big factor in what makes things cost way more then they should in the medical field.

if its advertised as 90% accurate, then the 10% dont have a case.

Sure, they can sue, but if they knew going into the test and using this equipment that there was a 90% success rate, then case will be summarily dismissed.

Now, if they advertise that this equipment is 100% accurate/success rate of detection, then you have a liability.