alt Hacker NewsFor comparison: GNU coreutils ls 9.4 is 139 KiB on my system.
BusyBox v1.36.1 is 2.1 MiB and has 272 tools which is just about 7.6 KiB per tool, so when it comes to space efficiency BusyBox is probably hard to beat.
The (probably statically linked) 9base-6 Plan 9 ls is 961 KiB.
Not a fair comparison because it only implements a small subset of the GNU ls functionality.