First, when it comes to tipping in the US, I pay between 15-20% pre-tax, never more than 20. If the service was really poor, then it is zero. Every time I have been presented with a check choices for "suggested tip", I have always found an "other" line to use.
Having lived overseas in both China and Europe, I firmly adhere to the "when in Rome" principle. Complaining about different structures will not change them ("why don't they pay them a living wage?"). I happily pay no tip when traveling outside of North America. And yes, the tableside devices that are ubiquitous in the rest of the world are slow coming to the US because businesses refuse to pay the extra fees. It is now becoming more prevalent to add fees because one is using a card. As I refuse to pay the fees, I simply use cash or my check book (how is that for an anachronism.. but it works).