Microsoft: Yes this seems strange, but this is actually what the users want - and we have tests to prove it - so we'll do it
Linux: RTFM n00bz! Ubuntu! Ubuntu!
Your statement is an overgeneralization to say the least.
1) Does Canonical operate a usability lab?
2) Would Ubuntu developers pay any attention if it did?
(1a) I care about usability a _lot_ and I don't have a lab. A simple pc in a room is quite adequate for most studies. (For some of them you don't even need a pc)
(2) https://lists.ubuntu.com/archives/ubuntu-devel-discuss/2007-...
The biggest usability issue Linux has these days is a holdover reputation from the '90s.
The second biggest usability issue is that it's not a Windows clone, so muscle-memory no longer applies.
That's not to say that Linux usability is perfect, but I find that for the most part it's miles ahead of Windows, it's easier to debug when things do go wrong, and Just Works out of the box to a greater degree (downloading drivers is so 1990s) if your hardware is supported.