Because Mac OS X Finder has always been kinda terrible. There was a lot of talk about this in the early 2000s and it's just faded away since the people using macOS now probably never experienced the good old Mac OS 9 Finder.
And its Windows competition Windows Explorer has likewise gotten worse and worse each revision of Windows.
Oh... Finder is the name of the default file browser? I always thought it was the search results that popped down from the top right search area.
Last Mac I was on still had OSX on it.
Thank goodness for Dopus.
lol, directory opus? I was using that on the Amiga way back in the day. I tried it like a decade ago, but it didn't stick for me. It doesn't seem to run on Linux, and it costs $$$, so no chance I'll try it again.
I can't think of a better rationale for the ubiquitous worsening of local search than increasing ignorance of comp sci fundamentals.
There's no reason a senior at undergrad level shouldn't be able to write an efficient, fast, deterministic, precomputed search function.
... and yet, professional developers at major companies seem completely incapable.
Minimum acceptance criteria for any proposed shipping search feature should be "There is no file / object in the local system that fails to show up if you type its visible name" ffs.