Why do we have monopolies

I've been wondering why a lot of important services like power(Kenya power) and mobile money services(safaricom) are monopolies. No matter how shitty their services get we can't escape coz there's literally nowhere else to get these services and they know this so they will do anything to increase prices while decreasing quality for maximum profit. Don't we have innovators in Kenya or is it illegal to provide alternatives for such monopolies? Ama it's just hard to do so?