Thank you for the kind words, Debbie.
You have your facts right about the tipping, but I think your logic in interpreting them is a bit off. Yes, there is an 18% gratuity added to meals and alcohol purchased with the Tables in Wonderland card. But you also need to tip your server any time you are dining at a table service restaurant.
18% is a standard tip level for good service. The etiquette books I consulted recommend 15% to 20%, with even more for extraordinary service or an elegant restaurant.
I think 18% is a fair gratuity for the service you will normally find at WDW. If for some reason you have terrible service that you didn't feel warranted an 18% tip, it would be perfectly within your rights to speak to the restaurant manager about having the tip removed or reduced, but I very much doubt that this will be the case.
If you were paying cash for your meals without the TiW card, you would still need to add a gratuity. Let's say I'm paying cash and my meal costs $100. I will then add a tip and pay the restaurant $118. If I have the TiW, my meal costs $80 ($100 minus a 20% discount). Then, when I add an 18% tip (based on the original meal cost), I end up paying $98. I've saved $20! I would rather pay $98 than $118 dollars for the exact same meal.
While the TiW card does cost $75 for annual pass holders like me (prices sometimes change), you can see that in just the example above, I saved $20. Four more meals like that and I've made back my investment and the real savings begin. Based on my family's dining habits, we found our TiW savings to be
very substantial.
Hope this helps.