I don't think I'm missing the point. I just take 'roger' from A/G as reassurance that my call was transmitted on frequency. It is a reply I might expect (if any) to 'ready for departure'
For Example:
Example Radio, 123.450, G-XXXX, radio check and airfield information for departure
G-XX reading you five, runway in use 07, right hand circuit, QNH 1001
reading you five also, 07 right hand circuit, QNH 1001
The above is a direct communication to the A/G operator, I expect certain information as the reply.
Next call:
G-XX taxi to hold 07
Here I might expect no reply from A/G, it's information to other pilots that I'm going to taxi to hold for runway 07. The A/G may reply 'Roger' I simply take that as meaning 'we heard and understood your last transmission'. Hopefully then so did everyone else on frequency.
I arrive at the holding area, carry out my power checks and pre-take off checks. At this time pilots on final can see me, they might be wondering is that aircraft about to line up?
At the end of the checks I scan the approach path and call:
G-XX Ready for Departure
The pilot on final who I didn't see now knows I'm ready to depart and is warned.
A/G may or may not respond 'roger' which means nothing more to me than the A/G Operator heard and understood my transmission. It was not actually for their benefit in any case, but hey I like our A/G operators so they can say 'roger' if they like. If they don't it doesn't matter much.
If they reply 'I have a spaniel dog' it conveys exactly the same information, but 'roger' is shorter and better R/T
