Nothing is normal in real estate.
It boils down to agency and HUD
In our mls you are able to offer 3 types of compensation other than the sellers agent side. No sub agency, buyers agency or facilitator. The sellers agent can state the amount being offered from 0% to 100% this is done with the sellers agent notifying the seller of this.
Typical buyer agency agreements state that the buyers agent will seek the compensation being offered by the sellers agent to the buyers agent. In the event, no fee is being given or an amount not acceptable to them, one would then look to your buyer agency contract and see the amount that you and your buyer agent have agreed upon.
Getting back to HUD the reason buyer agents seek their compensation from the sellers agent is that HUD has not found a way to incorporate the additional buyer agents fee in the mortgage.
In many of the transaction I have been involved in I have had my buyers pay my fee directly, primarily in commercial transactions as it is difficult enough to get a institution to agree on a sales price let alone compensation above it.
Hope this helps