I can assure you that from what I saw in Italy and France, the wait staff had no such issues taking tips from a North American.In Ireland TIpping is frowned upon..In fact bartenders and others are insulted if you tip them. They feel it is below them...as if your giving a few quid to a 'servant'
Having said that..they are paid an excellent wage to slug Guinness!!
Frankly, I felt really wierd leaving no tip.
Unless I saw on the bill a fee for "Service" (in the UK you might see 12%) I'd still leave a tip.