Telecoms monopolies are usually required to provide
fair access to competitors. BT in the UK provides a number of services to resellers and limited site access to exchanges to and cabinets. But that
open access only has to be fair by law, not free. BT gets showered in cash, both to maintain the infrastructure and also provide physical access. KPN will too.
Running Whatsapp isn't free. Their servers hold messages, handle authentication, developers need salaries. Third parties should have to contribute to this too. WhatsApp should get to charge for access to their infrastructure, Just like BT/KPN/etc.
But now you're in a situation where competitors either pony up and swallow the cost themselves —as WhatsApp does— or we also force WhatsApp to not undercut its wholesale price, to make it less tempting. Price restrictions are common in attempts to overturn physical monopolies.
Open access is a lofty goal but it also cements that protocol, those phone lines, that water pipe as the provider for that type service. It can also arrest the development of the base infrastructure, as well as putting people off developing their own alternatives.
Or... We get a bit more revolutionary about things like this. If somebody makes something that becomes fundamental to society, society buys it outright. [Inter]nationalise services (and drugs, and patents, etc). In this case, buy WhatsApp, federate the service (allow people to run their own nodes) and fix the addressing so it's like email. I'm sure somebody can make cases for and against that.
