Like a lock on your front door, the purpose is not to prevent unwanted people from ever getting inside (no lock will ever accomplish that), but to both make it take long enough the likelihood of being noticed is high, and to put enough hurdles in place that the attacker looks for a more lucrative target.
This is done through time, capability, and money. It takes time to jump through the steps. This presents risk to an attacker as it leaves them exposed for much longer, and susceptible to being tracked down in various ways as they expose themselves. It takes capability to jump through the steps, requiring the attacker having compromised the target in multiple different ways (phone system, employee, etc). This increases the complexity of the attach and thus the risk to the attacker. It takes money. This helps the providing company recoup the cost of verification (and if it's anything like web SSL certs is also about insurance), but money also provides another path to racking down an attacker, and provides a cost to them that isn't just their time. It also makes it less feasible to attempt a bunch of these attacks at once, as it's expensive.
People can complain about the inconvenience all they want, but the inconvenience is part of the point, so I doubt you'll see it change all that much.