Here in Texas, we normally have several weeks every year with high "official" temperatures over 100F (and over 110 is not unheard of and I've experienced 120 a few times) and it's not commonly reported about how this and that surface in the full sun is over 140 nor do we put thermometers out in the sun and claim it's accurate.
If it weren't the hottest week in Melbourne as a news reporting sensation, wouldn't these inflated temperatures readings still be proportional (if not the same?) to the official readings, i.e. if it were only 90F, wouldn't a black surface in the sun still be over 120F? Wow, that sounds really hot!!! but it probably happens all the time.
When you think about it, one has to take the accuracy of all historical temperature records with a bit of a grain of salt, since the kind of shelter providing the "in the shade" part of the formula has not always been standard. An analogue thermometer read by failing eyesight in a wooden box might conceivably give more variable results than a modern digital weather station like
these ones. At any given (manual) weather station at any given time the accuracy depends on the construction (and maintenance) of the weather station and the competence of the human recorder. There is even of course the possibility of local pride inflating or deflating figures to break a record. However, the overall picture and wider averages should be reliable as such possible vagaries even out over time.
