So let's say , to go back to the cleaning example. For all the work that you are doing, you are not only cleaning, you are also:
1) Helping the company retain an attractive office and therefore an attractive image to customers, which will help the company's profits to go up.
2) Saving the boss (or whoever) money on cleaning products and cleaning, which means they have more time to spend on their work, which will mena profits will go up.
3) Helping the staff to work better and more comfortably in a more comfortable environment, which again will help productivity and profits to go up.
And so on.
Surely this is part of what the "surplus value" is as well?
And you are not getting a proper share of that, you're only getting the minimum wage. That's what I always thought it meant. that the benefit to the employer (and the amount they could afford to pay you)is alot more than what you actually get in reality.