FWIW, those rules are relatively nuanced. It's not like someone ruled that Goldman can deceive all clients at all times in all transactions.
Typically it comes up in places where there's a question of whether the bank is responsible getting their client the best possible price in a transaction or whether the bank is acting as an arms-length counterparty who happens to be taking the other side of the transaction. It also depends on the sophistication of the client and whether it's a transaction where the client should expect Goldman to be bullshitting them.
Goldman acting as a bank for the Apple credit card is completely different from Goldman acting as the counterparty in a large FX hedge or bond deal.
Typically it comes up in places where there's a question of whether the bank is responsible getting their client the best possible price in a transaction or whether the bank is acting as an arms-length counterparty who happens to be taking the other side of the transaction. It also depends on the sophistication of the client and whether it's a transaction where the client should expect Goldman to be bullshitting them.
Goldman acting as a bank for the Apple credit card is completely different from Goldman acting as the counterparty in a large FX hedge or bond deal.
Not that I like defending GS