British vs. American Dialect in Translating ‘The American Granddaughter’

One thing is bothering me. The narrator’s diction is quite high---a working-class girl from Detroit says, "I pulled into the spacious parking lot in front of Wal-Mart…." Fine. Something has elevated this character, putting her outside of ordinary American speech. I haven’t read so far that I can see the full effects, but I can appreciate the decision.