The appeal to American Exceptionalism is their last line of defense. It doesn't seem like they've thought this through.
"No this doesn't work here because we are less densely populated!" (Trains)
"No this doesn't work here because we're more densely populated!" (Crime)
"No this doesn't work here because we're less racist!" (Social policies)
"No this doesn't work here because we're more racist!" (Also social policies)
"No this doesn't work here because we're less warlike!" (Foreign policy)
"No this doesn't work here because we're more warlike!" (General policy)
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I've only heard the first one. I've never heard of any of the others. I think you are making them up.. again to fit your argument.