How do you loot enemies in Wasteland 1? Is there some other way you're supposed to be able to pay doctors?

Lootbags in Wasteland 1 do not drop often.
Some lootdrops are hardcoded via location, like the random rundown building in Vegas with the invisible enemies that drop 1 Proton Axe.

If you need money badly, you could:

A) loot supplies from the Quartz Inn and sell them to various vendors (Quartz Weaponshop, Rail Nomad store + Highpool store).

B) wander over to Rail Nomads camp and pick a fight with some of the tribes, who do drop lootbags.

C) wander around in Quartz checking out buildings until you find Ugly's Hideout, which has alot of goons, but also many Lootbags with ammo + lots of cash.

Doctors in Wasteland 1 are best for curing diseases + radiation poisoning.
Try creating a Macro command to wait 20-30 turns, which will heal 1-6 HP, depending on where your party is. The Wasteland 1 manual explains how to setup a macro command, and the best place to heal up without being interrupted is the deep desert (requires canteens for all party members, otherwise heatstroke happens).

Thank you! For some reason I never thought I'd be able to rest in the game. It's a good way to gain experience too.

D) Find some anti-tank weapons and sell them; they sell for a lot more money than you would expect for a single use item.

Also, why isn't this topic in the Wasteland series subforum?

This Post is already fairly old - but since I just finished Wasteland 1 Original half an hour ago a couple of comments and observations:
You really don't need too much money in this game if:
1) You have at least two Characters with decent Medic Skills. These skills will make sure that you can heal your characters to the degree that they can later heal themselves just why resting. This will make sure you don't have to pay a fortune at the Doctor Shop just for healing hit points. Doctors are indeed just for curing.
2) You invest into Brawling skills - The beauty of Brawling is that it will give you multiple attacks and these attacks don't consume any ammunition, it actually allows you to sell ammunition.
3) As you do need in some fights to use you long range weapons you still need to develop the corresponding skills. But you can do this in a couple of locations very quickly. One is below a temple where you can after having cleansed and looted the area, you can activate a Defense Laser via stepping on purpose onto a plate. Then you use single shot to destroy it... very quickly the long rang weapon skills will increase. The second place, is Las Vegas with the Scorpion. So you don't need to worry that you fall behind in the long range fighting skills by applying just a brawling approach. In addition you do get in Las Vegas a very powerful axe "Proton Axe" and later in the game a second one. These do huge damage and if you have Level 7 in Brawling your character hits I believe 5 times...I came across only one enemy that I could not kill with these weapons. For the rest of the party you buy chainsaws for 500 each. So yes this is one of the few cases I would recommend to invest as you don't find those in loot too often. I just did once.
4) To do the Melee approach in Las Vegas you will need to buy also Kevlar Suits as otherwise you will be killed before you reach your enemy. These are expensive but thanks to 1) 2) and 3) you will hardly spend any money and the loot will add up.
Finally the Melee approach is also offering in the late game a very easy way to level up your character. I got board once I reached 2nd Lieutenant but this levelling up you can do forever. In one of the pictures I show the location where you need to stay, then just rest. Another picture shows how in the middle of the game you can kill the Scorpion just with Melee. Finally inside the game you find a location where they advertise Wasteland 2....many years before it really materialized.... t

Or you could just skip Medic and wait for Doctor.

Thing is, early in the game, enemies don't hit that hard, so having a character be injured is rare, as it's very likely that the character will be knocked unconscious, and unconscious characters are basically invincible. Then, once you can learn it, Doctor is superior to Medic.

Then again, Medic never becomes useless for a character who doesn't know Doctor, so not upgrading might be a reasonable idea, except that you need high IQ for the Energy Weapons skill, anyway.