Is it right that my Job wants me to get a doctors note for being sick for one day? Would a walgreens receipt showing medication work?

Check your employee handbook first, the thing that nobody reads. The company policy is there. I've never heard of a company requiring a note for one day sick during flu season, but check anyway. 

Doesn't matter how much the job pays. If your boss wants a doctor's note then get a note from your doctor. A wallgreens receipt for medication isn't the same thing. They want it to prove that you were too sick to work, or that you're well enough to come back to work. If you're calling off, they don't have to tell you that they got some one else to cover for you. You should know that they're going to do that. If you have a fever and feeling too sick to work, you should be at home and getting some rest. Go back to your doctor and get a note. 

It might be policy that requires a doctors note. It is possible they can fire you but I believe the most they'll do if you don't see a doctor to get the note they want is mark the absense as unexcused. The thing is that if you don't have insurance and don't have a primary doctor you'll have to find one and make an appointment and you're not going to get an appointment the same day. The only way you're going to get an excuse the same day is to go to the ER and get one. It's a waste of their time but they'll understand and give you one.

If the job is truly low paying what I would do is just take the unexcused absense. It's going to take another day (or more) to fulfil their ridiculous request of a doctors note for being out one day therefore you'll be out 2 days and they'll want an excuse for that too. Eff them...they don't pay you well enough to afford your own and don't provide insurance so it's pretty ridiculous they require a note for being absent ONE day.

Just let your manager know that you didn’t need to go to the doctor

Your job likely wants the doctors note to prove you are well enough to return to work, not to prove you were actually sick. If you called in sick with a fever, it makes sense they would have covered your next shift, because you really should be fever free for 24 hours before returning to work. Showing a medication receipt is not the same as a doctors note and probably won’t be accepted. You could simply tell your employer that you did not go to the doctor, so do not have a note and see what they tell you. If they insist on a note, you might decide it’s time to find a new job. Many people do not run to the doctor the first day they are sick.

It's perfectly right - within their rights to ask and fire you if you don't produce it. Don't produce a fake. They WILL call and check the appointment.

Probably not, but doesn't hurt to ask.

No. Anyone can buy medication. You don't have to be sick to buy medication. If they require a doctor's note, then you have to go to a doctor to get one.

No it’s not right. America is one of the only countries on earth where employees are not guaranteed sick leave. That’s one reason to never eat at a restaurant or fast food place. Because they force their workers to work while they’re sick and they get all of their customers sick. It’s stupid, bordering on pure evil. 

Right? Fair? Reasonable? Maybe not, but it doesn't really matter.   What does matter is your employer's policy and how much you need the job.

If you didn't go to the doctor before you called in, it doesn't really matter if you go to the doctor now - now isn't when you called in sick.  If your employer wants a reason to fire you, they will fire you.  If they don't, then they will take your word that you were to ill to work.