Not true. OP said she had drinks while playing in the casino, therefore you cannot go up to any bar to get a drink. If you have the "drinks included everywhere on the ship" you CAN go to any bar.
Also, you have to make an effort flag them down to get a drink. They will not just come to you automatically as they are extremely busy. Giving an additional tip may also help. My DH and I play all the time in the casino and never have an issue being served because we tip well.