Some interesting interpretations!
I am a mortgage broker and I can assure you we are not all the same but considering a basic loan takes over 20 hours of work to put together (correctly), the money is deserved.
Also most brokers don't charge clients, the banks do pay the broker. The broker does the role of writing the loan and collecting required docs for the bank, who then assesses the application.
There is usually an up front payment plus a trail commission, additionally a claw back provision where if the loan leaves the bank within 12/18months (av policy) then the broker is clawed back 100%/50% of what they had been paid. Yep we love to work for free

Brokers are also bound by Best Interest Duty, which was put in place after the Royal Commission. Brokers must act in the client's best interest which is why a heap of paperwork is required to allow the broker to make the best recommendation for a client. Banks can only offer their own loans (which may not be the best for a client).
Some banks are pro broker, some are not. Most banks would struggle to perform all the tasks in house.
My business also does all maintenance on client's loans, like top ups, splits, annual reviews (generally all the unpaid work) so the trail commission is earned too. Our annual reviews keep our customer's rates from creeping up out of cycle, and if the bank will not look at a fair rate for existing clients we look at alternatives.
There are a lot of really good brokers, a couple that are not so good. Generally brokers are there to help though and the numbers (of people who use us, and satisfaction) stack up that overall brokers do a great job.
My 2c worth