I would call my lovely Poland less and less a civilised world, but even here I can test whatever I want whenever I want in at least two big networks of private labs. I go to lab online shop, buy what I want (vit D costs ~$13), download a voucher with qr code on my phone, go to the lab and 5 mins later I can go to home. I have an account on their web app, later that day I have results and can compare it to all my previous results too, each thing with nicely visualised historical data on diagram.
What do you think was helpful in your snide comment?
It reminds people that the world is not the US. 30+ comments above and nobody pointed out the unspoken assumption.
The OP mentioned the doctor firewall. I don’t live in the US and have the same firewall.
It’s not a uniquely American issue.
If you don't tell us where you live, it's not such a useful feedback item. In many (most) places in Asia, you can walk into any clinic and order whatever tests you want if they are reasonable and exist. For alot of tests the results could be available later that day. You do pay, but the cost is usually minimal compared to say the US.
Canada. And sure, I could ask my doctor and he’d say “sure, if you pay for it”.