We all may be coming from different perspectives:

I think that many people on these boards are accustomed to different standards in terms of gratuities than many Americans.

What is commonplace in terms of gratuities among frequent travelers in large American cities is actually quite unusual elsewhere.

Sometimes I feel that the service at high-end, $100-per-plate restaurants in the US has been mediocre, and I feel strange in giving the 15% minimum that custom here dictates. (I will usually call the manager and suggest improvements the next day). Other times, I feel that the service at a moderate European restaurant has been superior, and I feel strange in giving the 10% maximum that custom there dictates. But both standards are customary in their home culture, and we travelers have the burden of learning and complying with these customs when we travel.