I suspect the author doesn't care much for historical accuracy because this is supposed to be like 330(?) or so years after ~1583 (mentioned in chapter 1) cuz I don't believe department stores had escalators and looked like that until more recently. Either way I'm enjoying the series.
I'm guessing there was a time skip happening? That I couldn't spot Or as others have said the author doesn't care much historical accuracy Either way still a good story