yes, that is true. But I'm talking if she doesn't even leave the confined area. Since invisible fences are "invisible" she will look free to someone passing by. That's why it's best to have the fenceline well back from public areas.
I've heard of people being sued because it looked like the dog was going to leave the yard and there was no visible barrier to stop them. The passerby steps backward from what they think is a loose dog, twists their ankle stepping off the curb, and viola. You have a lawsuit for medical bills, even if your dog doesn't leave your property. However, if the fence is well back from the road, the dog stops long before reaching that point.
I see a lot of people who have the i-fence running along the property line. Which leaves the dog free to run almost to the public area. And that also makes it more likely that a dog will run through - the thing they want is right there, almost touching, and they forget themselves in the drive.
Another potential solution if the dog is only out for short unsupervised breaks, would be to get some t-posts and put of the plastic netting used at construction sites. Or even chicken wire. Just something to denote to the dog that they aren't allowed past this area.