There's nothing actually stopping you from getting a fungal culture yourself. The turnaround time is over a month though. Unless you're at a huge hospital they just farm it out to Labcorp and the like and you can buy direct. Like it makes sense, if it's high-probability bacterial you might as well try the z pack first. It's faster to just treat it and see than to test if it's bacterial.

Also for SSRIs there's nothing to test, you just try them under medical supervision and if they help they help. There is an experimental DNA test that might be able to narrow down the antidepressant options but unless you're struggling to find one that works for you it's usually not worth bothering.

Medicine is crazy advanced in some specific areas but for the long tail we're not that far from leeches.