This question was originally made in response to NonCompete's 'Welcome to the CLASS WAR! - Why Capitalism SUCKS - Part 2' video, but I trust it's general enough to be asked here.

Background:

Bob makes bikes. His business grew and now he's hired Kate so that they can make twice as many bikes. The cost of the bike parts is $50. Bob sells their bikes for $100, but only pays Kate $25 (taking another $25 for himself).

NonCompete's assertion:

Bob and Kate are making bikes of the same quality, therefore should be paid the same.

Reasons why it makes sense to me that Kate gets paid less:

1. Bob's business got popular because he made good bikes. Kate did not build this kind of trust, therefore on her own, would not be able to sell bikes for $100. Bob's bikes are worth more to people, because people are more confident in their quality. And if Kate works for Bob, Bob can control that quality.

2. Bob has an existing customer base. On her own, Kate could not build as many bikes as she does when she works for Bob. She gets paid less per-bike, because she uses Bob's customer base to earn more in total.

3. $100-$50 might be the "value of labour", but that labour includes things like: finding suppliers, negotiating deals with them, marketing, planning, logistics, keeping standards, etc, etc. When Kate works for Bob, she doesn't have to do all that labour, therefore doesn't get paid as much.

4. If Bob's business is successful, his bikes will be worth more to people just because of their brand. That's different from them being worth more because their quality has been attested (point 1), but the result for Kate is the same: she couldn't sell the bike for $100 on her own.