Take the medical profession. You will pay more to get an injection/pap smear/whatnot from a doctor than from a nurse in the same clinic. Yet they are doing EXACTLY THE SAME THING! With exactly the same inherent value.
Do you think that doctor really has more training or experience in giving injections or taking pap smears than that nurse? In many cases, no.
Patients pay more because
a) the doctor has a lot of fancy letters after his or her name, and that must mean something, right?
b) the doctor has enormous student debt that they have to pay off sometime before they retire, much more so than a nurse
c) doctors have (as the numerous ones in my family tell me

) what is known as a ‘God complex’ - a sense of entitlement, a sense of superiority, a sense that they’re worth scads of money. Drummed into them as they go through their training. Unlike nurses.
Actually, that is not a good example.
First of all, you’re not talking about wages. You are talking about retail pricing of services where consumers hypothetically are given a choice of service provider. The price you pay not only includes the wage of the laborer, it also includes his/her overhead (things like utilities, rent, equipment depreciation, and so on) as well as the wages of any support staff (nurse assistants, medical accountants, and so on).
I will fully grant that the salary of an LPN or a PA is going to be less than the salary of an MD. But look at the scope of the person’s capabilities. Sure, either an LPN, a PA, or an MD can do a pap smear. But what happens if the pap smear comes back positive and additional tests are required to confirm cervical cancer and, God forbid, cervical cancer is confirmed? Is the LPN or PA going to be able to provide the treatment for the cancer? No, only the MD will provide that treatment. Because of that increased scope of capabilities, the MD should certainly make more than the LPN or the PA.
As far as wages are concerned, distributive justice, in theory, says that distribution should be made from a society to an individual in proportion to the contribution of that individual to that society. In a practical sense, this means that the society (the company) should distribute (pay) the individual in proportion to his contribution (looking at the skills and capability he brings and the revenue he generates for that company). An example of where distributive justice would be violated would be if you had two LPNs with similar education, similar capabilities, similar experience, and similar work ethic get paid dramatically differently, particularly if that distinction was made on an irrelevant factor (say due to the race or sex of the LPN).
Secondly, for the most part, pricing in the medical industry within the US is not based upon market factors. The reason for this is that most consumers of medical services in the US do not pay for those services. Most consumers of medical services pay for a portion of an insurance policy and pay a fixed co-payment for a provider. The actual “payer” of medical services are mostly large insurance entities (either commercial or government owned). That’s the way virtually all insurance schemes work, as well as Medicare, Medicaid, VA, and military insurances operate (although granted that VA and military also operate their own clinics that do not directly charge the patient either).
This dramatically distorts pricing. The consumer will typically pay a set co-payment for a primary care provider, whether that provider is an LPN, a PA, or an MD. The provider, in turn, generally bills the insurance entity who reimburses based upon their allowable pricing for a given procedure from a given type of provider. This allowable pricing is based upon data that insurers analyze to determine a fair market price. To my knowledge (and I am willing to be corrected by a person who is actually in the medical billing field), insurers typically will reimburse differently based upon the type of degree the provider has: i.e., they have different rates for MDs than for LPNs or PAs.
Naturally, in order to cause the reimbursable amount to increase, providers almost universally attempt to charge more than what the insurer will reimburse, even though the patient almost never directly sees this. If you have health insurance, all you need to do is look at an “Explanation of Benefits” from your insurer. For example, I just happen to have one sitting in front of me that shows that a provider charged $178 for a routine office visit (procedure code 99214). My insurer only allowed $98.95 for that visit. My portion was only $20. It wouldn’t matter to me if they attempted to charge $300 for that visit. The insurer would still only allow $98.95 and my copay would still only be $20. I really don’t care. All I care about is the $20 copay.
Where this causes a problem is for the small minority who actually pay cash for their medical services. Using the example above, many providers would expect $178 from the patient (though some will discount cash patients so they would only have to pay out what the provider would get from an insurance company – my dentist works like that for his cash customers). And that is where you’ll start to see the difference between the pricing for an LPN/PA and an MD.
If we dealt in a truly free market with the medical industry, then you would see prices go down. And while you would still see a difference between what an MD charged compared to an LPN/PA for the same service, the difference would be significantly less than what it is today.
But keep in mind the above discussion talks about prices, not wages. As I explained at the top of the post, the two are different.