Perhaps I should clarify that I meant in order for an employer to make a profit from an employee, they need to pay the employee less than the value the employee added through their labour.
No I understood - and I disagree. The employer can charge more than the value of the labor because the employer is adding value above what the labor provided. The labor can be fairly compensated and the employer still charge more than that. The "employer" adds brand recognition, sales channels, testing, distribution, indemnification, and all kinds of other things.
Sales price above value of labor doesn't at all have to mean they are paying the labor less than it's worth. Sure that's one way to increase profits, but it's not even a necessary condition for profit. So a statement like "an employer can only profit by underpaying for labor" is just hyperbole.
The employer also employs other people to do all of those things, either in order to be able to sell the product (sales teams, advertising, lawyers etc.) or retain employees (health and safety, HR, lawyers) to actually make a product you can sell.
At the end of the day, the difference between the value of the input and the selling price of the end product is a result of the labour that’s gone into it, and in order to make money off it, the selling price will need to be higher than the labour cost.
You can call it hyperbole, but… I disagree you on that point.
I am of the unwavering opinion that employers are lucky the employee has chosen to give up their time to work for them (and not a competitor!), not the other way round.