Another bit of incompetence that really winds me up is:
software that you can specify the install location for, so it installs a update manager at that location but then always installs the actual programs under the C drive
What the heck, I've never seen this. Hey ISVs, if you see this conversation engage me to consult on how to make your installers not drive people like us up the wall! ;)
IIRC Visual Studio technically lets you install in a non-C location but 80% of the disk usage ends up on C: anyway.
Microsoft decided at some point people hard drive were plenty big so who cares? Unfortunately SSDs came along and for quite awhile space was quite tight on them!