Wish they could do what routers, routing protocol and BGP does for the Internet. Can't get here, route around this way.
They can, but redundant power costs more. Some but not all substations will have more than one link to the grid, but it isn't going to be done for the line running down your street connection to your house.
If you're a major commercial customer you can get redundant power, a lot of larger companies will have two or sometimes even three separate utility feeds from different substations (and even different providers if they're near enough to another) But I'm sure that's not cheap.