I understand mandatory gratuity if you have a large party (most places state such if it a group of 8 or more... some even if it is 6 or more). The reason for that is because a large party is substantially more difficult to serve... usually requiring multiple servers depending on the size of the party. However mandatory 18% for 2 people... no wonder the service is horrible. The servers have no incentive to "hustle" if the tip is automatically included. If my service was that bad I would have the 18% removed... but that would be a drop in the bucket because I doubt a lot of people would challenge the tip.