Excellent discussion, some history and some fine real-world information.
Yes, we spend a lot of time reading the specs and hitching our wagon to them.
I know there must be a reason company engineers choose to go down a path, especially if the design and layout and internal programming are already done.
I know that even the expensive (for its time) ID-5001 had major problems with the humidity sensor. Yet temperature on this, and the now-defunct TWI was usually extremely close to my precious mercury thermometers with gradations fine enough to resolve about 1/2 a degree.
Its interesting to hear the platinum wire sensor wasn't as accurate in those settings (I know we're talking humidity here) but a R M Young device has a platinum wire sensor and is very expensive so one would think that if there weren't accuracy behind it, even the US Government and Universities with deeper pockets would opt for the method that gives best results.
Anyway, I know the precision of some of the accurite home monitors has been exceptional (hard to know accuracy since I don't have any way of testing them in a controlled setting like a salt controlled humidity environment like the calibrators for Vaisala and otherss. But over all, through humid summer and now fall and entering into heating season indoors with the floor creaking low humidity, two of them are always the same or withing digit bobble of the same.
But I'm not sure what technology they are using.
Are all the Arduino sensors using the same technology as the SHT uses?