But all things are not fair and just. The capitalist pays you for the cost of your labor-power, not for the value of the goods you produce. Thus your paycheck is worth the value of your labor-power. But your labor-power is set to work to produce commodities of greater value.
Let’s say you work for Starbucks and they pay you $120 for an eight-hour shift. But you can probably make $120 worth of fancy coffee in an hour, or probably in a half hour at a busy store.
Even once you subtract the cost of materials and use of the equipment, Starbucks doesn’t pay you anywhere near the value you’ve created (hundreds of dollars a day). They buy your labor-power from you, not the actual fruits of your labor. And you make that value back for them in an hour. The rest of your shift, you’re basically working for free!