In NYC, the typical non-negotiable broker's fee for a not-disintegrating apartment ranges from 10-15%. That's on top of a security deposit and all the other costs associated with moving. It's a cartel that can only be broken by collective political action.

Things are slowly moving in that direction, only because the pressure has been so high for so long. It almost boiled over during COVID in some neighborhoods. There are still works of "Abolish Rent" graffiti left over from that time.