Right OK isn't RGB SCART essentially the same as component video? ie 15khz not 32khz horizontal refresh? Whether your TV set supports 50hz over component is another matter but suspect quality brands from major Japanese companies will do.
I suspect after a little googling that you can indeed use the RGB SCART signals in some form to connect via the component input of Plasma/LCD TVs. The circuitry will certainly be in the TV to accept said signal, it's just that USA doesn't use the actual SCART connector as a standard. All HD TVs have pretty much identical insides nowadays regardless of whether they're destined for shops in the UK/US/Japan. Would cost way to much to do bespoke PAL controller/input boards for LCD/Plasma HD sets sold here to add extra essential 50hz optional modes for our SD TV equipment to be connected, and many cable/satellite boxes still only use SCART RGB. In 60hz mode it will definitely work via the RGB-A output of the Amiga.