Hence with 1.7 billion people staying unbanked, added to the increase of people who don't rely on banks, Bitcoin provides them with numerous options why they should use bitcoin for different purposes like sending money to relatives in different countries at a very low fee.
The problem most of these physical entites like banks have is that having to spend on building banks, they still need to employ people to manage there and some these are challenges because it is most at times hard to get people to live in remote places like this. Other thing again is the fact that most of these rural areas hardly use the banks daily, the only go to them either monthly when they receive there salaries or wages or when they have issues. So putting in employees there would only be waste of resources by the banks.
bitcoin actually solves all these issues since it doesn't need any physical entites but the problem is you need the internet service which are somewhat not available in these places or the knowledge which is needed to set up wallets or how to protect it. Also these set of people hardly trust anything that the government didn't approve, so adoption of bitcoin in these areas is still not feasible just yet.