I insist that someone do something.
(used more in American English, says Michael Swan's Practical English Use , for instance)
I insist that someone should do somehting.
(used more in British English, says the same)
Why did the present subjunctive survive in American English better than it did in British English (outside fixed phrases such as "God save the Queen!") when, on the other hand, forms like 'burn t', 'leap t', 'travel l ed-travel l ing' did not, and were made regular?
Is American English more archaic or more modern than British English?