The military tends to use helicopters in favour of A380s to deploy troops to combat areas, therefore A380s cannot land on Earth. It's inconceivable that a shuttle might allow you to land troops more easily closer to the target.
Ok....I actually wasn't disputing that fact.
It was my recollection that due to it's increased size, etc. the SR2 could not land on planets, as opposed to the SR1 where we seemed to land everywhere. To use your example, with some cursory Googling I found that the A380 seems to require a few thousand feet of runway to land, now if you played a game where they had one land in fifty feet, it might cause some surprise and wonder if they had an explanation or whether they were just ignoring the pre-established parameters for the plane.
However ImaginaryMatter and Invisible Man were kind enough to furnish me with further details on the matter, that it is high gravity worlds, and that it had landed a few times which I didn't remember. This is why I said 99% certain, so I still had an out. 
Don't see why it wouldn't be able to entier the atmosphere or even hover with the big eezo core. However I suppose it's possible that it couldn't support its own weight if landed and powered down.
Yeah not sure, I assumed it was something like how Dreadnoughts couldn't enter planets or how the Reapers had to drop or weaken their barriers in order to land on a planet. But it has been over two years since I played ME2, so I'm operating from memory here.