"Why oh why, when at EDI and at GLA do we have to read back this most unnecessary, annoying clearance before taxying:"
Because I have been instructed that I MUST issue this clearance which I find unnecessary and annoying but it needs a readback.
"Lets face it, the runway that the undershoot belongs to, is closed 99% of the time. "
Just because you don't request to depart/land on it does not mean that it is not available. Speak to a Flybe Captain.
"Also, think about it, when landing or taking off we also cross the same airspace as the undershoot, just a few meters further, but we don't get clearances like "Clear take off/to land AND clear to cross the damn undershoot!"
No s**t. Try telling that to SRG and the BAA who told us we had to do it.
We don't like it and complained bitterly about it but do not have a choice and it is a pain in the arse. It's also inconsistent as not all the runway entrances have the markings but it is here to stay.