It is not that simple. Just because Bitcoin is faster than a bank transfer does not mean that for many it will be a fast and simple solution.
There is no infrastructure. For example, you have money, and you want to transfer money to your relatives. You need a wallet, and they need a wallet. You need somewhere to exchange the wallets for money. Those to whom you transfer, too, will need to find a place to exchange the bitcoins for cash.
And if he doesn't have it all, he'll have to create it all and understand what and how. Many people are very conservative, especially the older generation, and it will be easier for them to wait 2-3 days and get their money safely in the office than to go into all these wallets, transactions, and all kinds of exchangers.
Thank you, though the length of time of delivery of bitcoin may be short but the processes too may not be that easy for many, just that we are used to it in our ages. The older people will actually like to do it the way they understand and think will be safer. So we cannot blame them. Some people still don't know how bitcoin works and are not ready to worry themselves as long as they have alternative.