Recruitmen interviews are essential steps in the hiring process. They allow the recuiter to discover the candidate ,their personality, their skills ,and to determine their cutural fit.
Hiring Manager uses more of a hand on training. If you mentioned that you did Bookkeeping, he will put you on the computer so you can proof to him that you know. It also goes for the cleaning staff. He will provide training after you proof that you at least know your work.