Having been here for almost a week now I'm finding that 90% of Bermuda restaurants add an 18% service charge to parties of any size... "for your convenience a service charge has been added." They could've come up with a better way of saying it, and you really need to be careful to read the bill since the credit card slip generally doesn't make any mention of it. Drinks ordered at the bar normally don't get this fee.
Instead of these endless arguments over percentages and such, it's so much easier to realize that there's a social norm for tipping everywhere, and said norm is different depending on your locale. At least, that works everywhere except in the US...
I will say though that it seems like there's been a fair amount of "tip inflation" happening lately. Used to be people tipped 15%, pre-tax, for good service and only hit 20% for absolutely outstanding service. Nowadays, you get people who tip in excess of 20% for mediocre service. This changes societal expectations, and in turn "raises the bar" for everyone else. I'm not a fan.