@Transactional 위치와 적용에 대하여

[질문 내용]    
@Transactional
    public void accountTransfer(String fromId, String toId, int money) throws SQLException {
        bizLogic(fromId, toId, money);
    }
    
    public void bizLogic(String fromId, String toId, int money) throws SQLException {
        Member fromMember = memberRepository.findById(fromId);
        Member toMember = memberRepository.findById(toId);

        memberRepository.update(fromId, fromMember.getMoney() - money);
        validation(toMember);
        memberRepository.update(toId, toMember.getMoney() + money);
    }

안녕하세요. 강의 코드와 같이 accountTransfer을 실행했을때 트랜잭션이 잘 작동되어 오류가 발생했을때 롤백이 실행됩니다.

    @Transactional
    public void accountTransfer(String fromId, String toId, int money) throws SQLException {
        Member fromMember = memberRepository.findById(fromId);
        Member toMember = memberRepository.findById(toId);

        memberRepository.update(fromId, fromMember.getMoney() - money);
        validation(toMember);
        memberRepository.update(toId, toMember.getMoney() + money);
    }

이 코드 또한 그렇습니다.

    public void accountTransfer(String fromId, String toId, int money) throws SQLException {
        bizLogic(fromId, toId, money);
    }

    @Transactional
    public void bizLogic(String fromId, String toId, int money) throws SQLException {
        Member fromMember = memberRepository.findById(fromId);
        Member toMember = memberRepository.findById(toId);

        memberRepository.update(fromId, fromMember.getMoney() - money);
        validation(toMember);
        memberRepository.update(toId, toMember.getMoney() + money);
    }

하지만 이 코드에서 accountTransfer을 실행했을때 트랜잭션이 작동하지 않습니다.

이유가 무엇일까요?