The US sites that offer meds through a simple generic medical questionaire are far more into the gray area of the law.
When you do not talk to a doctor, you are not having a consult in my opinion. As it is the OP's that are in the US that offer consults are in the gray area of the law, but the ones that do not require medical records and do not require that you speak to a doctor are the ones that many states are trying to shut down.

Is it legal? Well...for now yes, provided it is legal in your state. Nevada for instance has laws against internet sales of prescription drugs unless you have had a face to face consultation with the doctor prescribing the medication.
You need to look up the laws for your state that govern or regulate what residents can legally do or not do.
Federal law is the basics. States can bulid on that and increase penalities and create more regulations.

You might try searching google for prescription monitoring programs, and also state pharmacy regulations and prescribing regs.

There is not a single answer as states differ on the amount of regulation they have enacted into law.