Why not "The police is after me"?
Is it that the swedish speaking have in mind "The police ARE after me" when they say "Polisen är efter mig"? (In the same way that in english they say "people are" while people is singular and are is plural? )
By the way, as I am neither native english speaker "the police are after me" can be used in english?
I think American English assumes the 'police' are multuple policemen and/or women, so it's treated as a plural because it refers to a group or organization. You can have one cop literally chasing you, but the policeforce as an entity would be after you, if that makes sense? With your Tesco/Wal-Mart example the speaker could mean an individual store is good (Wal-Mart would be the single store so "is") or the chain/brand as multiple stores are good (multiple stores so "are"). It would depend on the scale of context.</pre>