Well those instant swap is always charge higher fee, similar like Bitcoin ATM. Your brother is too ignorant for not looking how much the fee that he have paid to the site. This is why many people are advising you shouldn't buy Bitcoin when your money is still small, you need to accumulate it and then buy Bitcoin, so the fee wouldn't really hurt you.
As per my experience, the instant swaps and bitcoin exchange rates are higher on third-party sites as compared to Binance or any popular exchanges. Also, the withdrawal fee will vary from site to site and wallet to wallet and there is no standard here. Some may charge you extra while others may have nominal charges.
Bitocin ATM and shopping sites using Bitcoin also charge higher rates and I guess they do it because they think that the customers won't notice the difference of 5 to 10$.
Also, I noted that buying the bitcoin from inside the wallets is more expensive as compared to buying it on exchanges.