Those are examples of non-standard grammar because they're used in non-standard dialects, not because they end with prepositions. At where is he? does not sound any better, ...

Legal language has an unfortunate reputation for many reasons. Since legal style clings to archaic words, structures and non-standard grammar and punctuation, it remains out of step with modern ...

English grammar, beloved by sticklers, is also feared by non-native speakers. Many of its idiosyncrasies can turn into traps even for the most confident users. But some of the most binding rules in ...