Actually, some breeds probably could do as much damage. When I first had my rescue lab, he pulled me off my feet a couple of times. I'm 6'2", and 16 stone, and he is not even 4 stone. His bite pressure is approx 230 to 250 psi, which is more than capable of breaking bones, and his teeth are still sharp enough to rip skin and muscle from human flesh. Granted an XLB has a stronger bite strength at an estimated 300 psi, however this is semantics. A lab could still do you considerable damage.
The difference is that they usually give some warning where the XLBs have been reported not to. Labradors have also been selectively bred not to be aggressive, however there will always be rogue dog. If you consider that there are an estimated 100,000 XLBs in the UK, and low double digits have gone fatally rogue, there is a low percentage chance. There are more labradors, and less instances of fatal attacks, but labradors have definitely killed people. In fact between 2005 and 2015 in the USA, two people were even killed by chihuahuas, so they can also kill. Don't get me wrong, nobody here is minimising the impact of a fatal dog attack, or saying that the XLBs are not more likely to be problematic, or that the impact is not likely to be more severe. Despite the fact that mine has pulled me off my feet, I am not in any way concerned that he would bite anyone without warning or cause. If he did, the chances are that it would be a warning bite as opposed to a full in attack.
Does this mean all dogs should be put down, despite the fact that a wife is still statistically more likely to be murdered by her husband? Should we stop driving in case we have a fatal car accident? Essentially, nothing is without some risk, it is really what has been deemed acceptable risk.
If you don't like what the government have done to mitigate the risk, there will soon be an opportunity to vote a new government in. Even then, we need to lobby them to regulate breeders and outlets as banning the breeds clearly does not work. There are more pitbulls in the UK now than there were before they were banned, so clearly banning breeds does not work.
You've hit the nail bang on the head with the statement that owning one of these dogs is selfish with children in the home. This just proves that regulating the owners is an incorrect course of action.