That is correct. For non-residents, it is now the first $80,000 which is tax free (it was $72,000 and then increased by $2,000 a year for several years) After that it is pretty much a flat 15%. The problem comes in the first year or two of living abroad when you may not have met the requirements and then COULD BE subject to double taxation. That being said, in the cases above (UK and France) there are taxation treaties between the countries and you should never be paying double tax for more than a six month period. Even having done that tax credit can be obtained from the US for any double taxation involved.
Other countries which tax their non-resident citizens---Phillipines and Libya!!