No one is stealing your professional fees...this setup I'm referring to is a profit sharing model. They all make the SAME base salary of $400ish. Now the new associate does not profit share the facility and group profits because why should he/she - he didn't pay for any construction or negotiate any contracts? In a good year, this profit share is ~$400k additional. In a bad year like 2020, they actually lost money and made less than the new grad. PPP made it all a wash.
It would be ridiculous and extremely pretentious if the new associate demanded to profit share and make $800 in the first year like all the partners.
Imagine joining a business with another partner. The other partner invested all the capital and had been running it solo for 15 years. Now you join and expect to share the profits from day one? Without having to endure the initial 5 years of low revenue, business loans, negative profits to get to where the business is. Do you think it's fair for someone to sink in all that money and sweat equity then you walk in and expect a 50/50 cut without having sunk in a single dollar? You'd be laughed out the building.
You seem like you prefer a salary job where everyone makes the same, which is fine. But don't knock others who have a more growth mindset and are willing to trade equity and labor early for higher future returns. As long as it's not predatory, those groups certainly lead to higher returns in the long run. Also it leads to far more satisfaction working for yourself/group than working for a corporation. You are personally vested in the groups growth, success and relationships.
You're absolutely right that groups where they decide to pay you less just because you're new and advance you to a false equity-free "partner" after are corrupt. You also probably haven't seen a true profitsharing partner track since they're so rare and NOT advertised now.