If a dog gets out, they bring the others in, turn off the system, get the dog back, turn the system back on.
Tell that to the dog that starved to death.
Unless the dog can enter the yard, I would not want that system. I would consider alternatives.
The dog may not get out but plenty of critters can get in. ANd if those critters are bigger than the dog, the dog is now trapped.
But speaking of invisible fences... Had a friend with a big dumb Chessie named Roxie. We were hanging out one day and Roxie saw a squirrel in the distance and went full on sprint. As Roxie approached the yard boundary, we saw her brace herself for the shock. Roxie took the pain and was so proud of herself she almost forgot she was chasing a squirrel. Realizing she was free, happily wagging her tail, off she went in search of the squirrel with my buddy not far behind, “ROXIE!!” :-)