I must admit I'd wondered that myself.
"G-ABCD request taxi with kilo, QNH 1014"
compared to
"G-ABCD request taxi with kilo"
It's an extra check, to be fair, but exactly why under those circumstances do we read back QNH? Personally I usually listen to it twice to check the figures anyhow, and I assume most other pilots do as well.
Does anybody ever read back an incorrect QNH off the ATIS that warrants the tiny bit of extra time on the RT? Or is it a mechanism for ensuring that we're not so lazy we don't listen to the ATIS properly?
Not a big deal, but a fair question.
Assuming that actually was the OP's question.
G
N.B.
So IMHO when inbound at a flight level, the ATIS code is sufficient, no need for QNH.
- negative, ICAO standard is code and QNH, as is the UK standard and I *think* the USA.