In terms of maintenance and pilot training, I agree those countries are probably very safe. I don't know if I trust their security as well. But I also don't think U.S. levels of security are always that needed - the fact is, passengers would react so differently post 9/11 that you would need a fairly advanced way of incapacitating them. Box cutters wouldn't be very effective, although could still obviously hurt someone.
For me, the problem is much more fear of mechanical failure. I know the U.S. does a really good job checking its planes and making sure procedures are complied with. Nothing is perfect, of course, but the airlines don't want the liability. When a plane hasn't departed from the U.S., I still get concerned that something may have been missed in the maintenance department. I would also want to know how careful they are about letting flights depart in dangerous weather conditions etc. It's a pain to have a flight canceled, but the financial motive of airlines makes me wary. Of course they want their planes to fly as often as possible with as few breaks and expenses as possible - that's only natural. But sometimes even minor deviations from procedure to get a plane on the ground can be catastrophic, like those cases where the screws didn't get put back in or where there was tape left on the pressure sensor....
ETA: Someone I know who has been to Israel claims Israel maintains security just by asking questions to try and discern who you are, and avoids the "invasive" tactics of the U.S. in terms of physical screenings and limitations on what you can bring on board. I know Israel is good about security, but how does it differ from the U.S.? While I know there is a lot of value in sizing a person up, I find it hard to believe they'd be able to pinpoint every single sinister person by chatting.