The reason it works like this is that the user is forced to use the software. It should be the other way around. If people are forced to use something developers should do what they can to not make the experience incredibly annoying.
Sure, there can be situations where you need to cut corners but this is the log in screen.
After logging in I mistype an application name in the search box and wait for the dialog to pop up that says "Best matches" with an empty list under it. It can't even find "tunderbird"
If I type a single letter it shows "search teh web for "a".
But it does show Atom! Woah! Technology at work!
I get to chose, I can press the down arrow and select "apps" then press enter twice OR I can press the down arrow twice and press enter! Becareful! Dont press the arrow to fast or it jumps back to searching the web for "a".
No one put any thought into this process.
You're making an uncharitable assumption about real people who work full-time on this stuff. I can assure you that they do put a lot of thought into their work. No, I never worked on the Start menu or search myself, but before we started working from home, I was in the same building with the folks that do.
If you try running a screen reader, such as Narrator (built into Windows; edit: turn it on and off with Ctrl+Win+Enter, even on the logon screen), you should find that even if the focus somehow gets away from the Password field, you can get back there with the help of speech output. Logging in blind doesn't have to mean logging in with no means of orientation.
(Disclosure: I'm a developer at Microsoft on the Windows accessibility team, working on Narrator among other things.)