The flip side of cargo cans) being inexpensive and everywhere is that, like modern rail cars and shipping containers, they get misplaced, repurposed, dumped, you name it.

There is a (non-canon, I think) Trav ship that is a pair of spaceships bolted together to qualify as minimum tonnage for a starship, and a stardrive tucked in there somewhere. Kinda makes me want to do that but with cans: put a drive pack on the back of some welded-together cans, with a cutter or shuttle to serve as bridge. It would never make atmo, and it might be slower than the usual getting between orbit and gate range, but if you're desperate enough...

If one accumulated enough passenger cans, one could put together an improvised orbital habitat. Just keep shuttling passenger cans to orbit and welding them together (with the occasional decommissioned drive pack to keep everything powered, etc.) until you exceed the structural integrity of whatever you're welding them together with. Seems fine.

There's probably some overlap here: a refugee "station" in deep space, that eventually someone re-commissions one of those drive packs and lights it up to go somewhere. Very desperate measures.