It's quite possible to do transatlantic flights stopping at Bangor without them being EROPS, taking a somewhat northerly track to keep within range of Keflavik, Gander etc along the way. Sterling Airways of Scandinavia used to do Caravelle charter flights across the Atlantic in the 1970s. The ICAO requirements at the time I believe were 90 minutes, as opposed to the US FAA requirement of 60 minutes, so non-US registered aircraft would run to this level.
Once ETOPS requirements came along, they were quite onerous and expensive for a carrier to get and maintain, with significant requirements for engineering and crew standards, extra MELs, etc. Even nowadays, ETOPS operators with a deferred item can take a non-ETOPS track when necessary.