Assuming that we are considering an electronic thermometer for home use -
1) How much significance would any reading be given?
2) What "treatments" would be instigated or withheld depending upon the reading?
I would suggest that - in the home environment - the temperature is only really used to confirm what you already know. Your child is clearly unwell, you use the thermometer and, yes, they have a fever. But, as I said, you probably knew that already. My mother just used the back of her hand to "measure temperature".
What "treatment" would be instigated or withheld? Well, most likely the ill child would be put in bed with fluids and paracetamol (Calpol)/ aspirin. But that would happen whatever the thermometer did or did not record.
Let us now imagine that the condition of the patient deteriorates, so professional medical attention is sought. So as part of their initial enquiry they will ask for the "history". Significant facts here would be "started feeling unwell 12 hours ago, then 3 hours ago became semi-delirious and could not cope with the light being on". Maybe you can state that 12 hours ago temperature was 38.5C and 40C 3 hours ago.
From that there are clear signs that could cause grave concern, but the temperature readings are only a small part of that. The "trend" is clear, but the rapid deterioration of the patients condition is obvious. Again, what delay to treatment would be likely? The clear signs of rapid deterioration and the photophobia, particularly in a paediatric patient, would "set the alarm bells" ringing and demand immediate further investigation.
So, as I suggested earlier, in a home environment, a clinical thermometer has little, if any, clinical significance so you can be justified in claiming "Class A" designation.
In a hospital setting, where by careful use of timed readings taken using a standardised method, much greater significance can be given to the readings. It should be possible to detect an infection starting before the patient starts to feel unwell, or in an incapacitated patient (not communicating) the elevated temperature may be the only sign. So the temperature reading is much more significant in the choice of treatment, so elevating the risk level of any device involved.