I agree. The prices are so inflated and the restaurants so busy I guarantee you those servers are grateful for it all and not cursing the 'table of one' or the 'dessert only' folks. If you order a $6 dessert and water and take up the table for an hour, yes, I think your server deserves more than $1 or even $2 (of course). But a Monte Cristo is $17. I'm sure they're happy to make the standard (in my book) 20% tip to slide yours in a box, which probably frees up the table for their next guests sooner anyway.
It's sad to think but I bet a lot of DL guests are foreign (or just plain cheap) and don't tip them at all. Which does not mean anyone else has the right to tip them less, but just in the big picture I think they're ok with not everyone feeling like they need to spend a lot or tip on a huge bill, regardless of what they spent.