The problem is the lack of threat validation by police. There are many options now to validate threats, we have tech that can see through walls, robotics, drones. The fact is you have a very real chance of being shot by police without a trial and based on a phone-call.. and we are considering that a problem with the phone company?
There is no requirement for a company to let anyone make a call without have some identity confirmation.
Other than that, I agree few (no?) other countries have quite the same level of murder-by-cop (with or without swatting calls) as the US does. This seems to be at least in part due to the US police forces having ensuring that police are never liable for anything, and having got legislation to ensure that any "fear" of harm to themselves warrants immediate lethal force.
Independent of that though, they could attempt to call the house. Unclear how they dealt with these sorts of situations before SWAT was developed.