> You can get basically any medication or vaccination you want in the US as long as you can find a doctor to write the prescription.
Is that not usually true in other countries?
I doubt you need a prescription for most vaccines. Typically there's some sort of guidelines that might say normally given to over 55 years old, but there will be some wiggle room due to other hard to prove preconditions such as family history of xxx or sensitivity to yyy. You say you have one of those things and Costco or the public health dept. will give you the vaccine no questions asked. For example when the COVID-19 vaccine was rolled out it was supposed to be for older people, but also people with various other (not easy to test for) preconditions such as asthma. So everyone who wasn't an anti-vaxxer developed asthma.
Medications are different. Need prescription for that, although $$ and a zoom call can solve that problem.
There is a large industry in the US that specializes in catering to people that want medications, vaccines, diagnostics, and treatments that are outside the recommended standard of care that medical insurance or public health systems cover. You have to pay for these services directly but the market is competitive so the cost is quite reasonable.
A doctor must sign off on these but that step is mostly performative outside of some narrow exceptions. My impression is that this type of medical care is much more accessible in the US than most other developed countries.