[notahacker]

The mental exercise is fine for realising that satellites don't look as big as pictures of satellites in graphics, it's just missing the point that if you don't want to hit a 20cm x 20cm x 20cm cube that moves at 17,500 mph and has slow and limited capability to adjust that movement you need to allow it quite a bit more space, and be able to predict its movement accurately relative to yours. Especially if any collision means thousands of pieces of shrapnel that continue to move at 17500mph for decades or more, whilst potentially being too small to track but large enough to do a lot of damage.

Trains take up a negligible fraction of the mileage of the lines they operate on and rarely cross other lines, but signalling is still critical.

[southernplaces7]

All of these are useful things to keep in mind of course, and they're why I put forth my consideration as a thought experiment for perspective, not so much as an absolute assertion. Orbital space is complicated, and the the ramifications of accidents are extremely unique compared to those that apply in a terrestrial context, but I still stand by my point about it being absurdly big enough that a sense of proportion is needed in worrying about something like Kessler syndrome.