Capacity at the teleports is probably pretty easy to upgrade. If possible they're near internet exchanges, and if not, they've most likely got good fiber connectivity and can update the optics on both sides to get more capacity easily.

Maybe they've got some sites in the middle of nowhere, but I'd bet they worked with fiber vendors to pick places that were easy to hook up to existing fiber, because why not. I think I recall seeing someone had done some sleuthing and found that the teleports were sometimes being placed along rail right-of-ways, where there's often also fiber and maybe even power.

Capacity is still a cost factor. But they do choose places on major fibre paths. They have a sweetheart deal with vocus in oz, and as far as I can tell, they do their best to colocate.