It would be a vary rare and extreme case in the private sector if someone walked into a high-ranking position with no experience of the role or industry whatsoever, and one which no doubt would deservedly cause uproar from existing employees if it did.
Indeed, it's a difficult path to the top even for someone with a wealth of experience at the lower levels, despite those candidates often having more knowledge than those at the top in regards to the day-to-day operations.
Even when you are at the top, relevant experience generally limits movement from job-to-job; it's unlikely the current head of the NHS would walk into the position of CEO at a national chain of builders merchants, or that the current CEO of a supermarket chain would find himself Editor-in-chief at a national newspaper.
All this makes sense of course- why would you give such an important role to someone with no experience, particularly given that for any given job vacancy there will be a raft of candidates who do have relevant experience and proven track-records?
How is it then, that the only prerequisite for some of the most important positions in the country- education secretary, health secretary, defense secretary, home secretary, etc, etc- is to be an MP? How can someone with exactly zero experience in the sector or industry be put in charge of it, and moreover transition from one position to another as easily as changing their clothes?
It's no wonder that everyone- employees in the relevant sectors and laymen alike- complains about the running of things, because when you think about it it's sheer madness, and something that could only happen in government- no other organisation would be stupid enough to operate in such a way.