American English Use subjunctive more than British English and also they heavily use modal verb "would". Grammatical moods like subjunctive in many European languages like German and Spanish are stronger than British English. So is it correct that non-British European immigrants influence modality and moods of American English?
following is from The subjunctive in Present-Day English page 144:
A number of possibilities are put forward by Övergaard as reasons for the return of the mandative subjunctive in AmE at the beginning of the twentieth century, all of them speculative and almost impossible to prove. These include the influence of the native languages of the large number of immigrants from north-European backgrounds and the importance of the Authorized Version of the Bible and the Book of Common Prayer, in which subjunctive forms are prominent features. She points out that these books represent ‘practically the only English that all gentile immigrants . . . came in contact with’ (1995: 46). Regarding the increase in the mandative subjunctive in BrE between 1960 and 1990, Övergaard follows commentators such as Quirk et al. (1985: 157) and Gowers, in his edition of Fowler’s Modern English Usage (1965: 595), in ascribing it to the influence of AmE and the growth of mass media after the Second World War, as a result of which ‘American texts of every kind flooded Europe, and their impact on BrE evidently led to renewed availability of the non-inflected subjunctive, causing what appears to have been something of a sea change’ (1995: 51). In summary, Övergaard’s monograph is clearly a major contribution to the understanding of developments regarding the mandative subjunctive in BrE and AmE in the twentieth century. The evidence of the revival early in the century in AmE and the later revival in BrE is very strong. Yet certain things need to be borne in mind when referring to her findings...