They aren't slow and expensive, it's very cheap to send and receive money from any place to any place within minutes. Lots of people in my region use money transfer services. Btw Bitcoin is not a very good competitor in terms of speed and price because when transaction fees are high, Bitcoin fees can be more expensive than the fees of money transfer services and in terms of speed, Bitcoin sometimes need at least 1 hour because many companies don't accept transactions with lower than 6 confirmations.
Not to mention, bitcoin's volatility is also an issue to consider when using bitcoin as a currency or a method of transferring money. Bitcoin is very sensitive and even a small news can cause Bitcoin price to dump immediately, and while waiting for the transaction to be confirmed, our money can also lose value due to the drop in bitcoin price and not everyone is comfortable with that.
I agree with you, bitcoin is not a competitor to traditional forms of money transfer nor is it a perfect alternative.
Btw altcoins like XRP and Litecoin are very fast and cheap solutions compared to Bitcoin. Bitcoin shines in decentralization.
When it comes to remittances and payments, what people care about is transaction speed and fees, and it is clear that altcoins outperform bitcoin when it comes to domestic and international remittances and payments.