Ask HN: Is mobile network (radio) regulation technologically necessary?

Well, that depends if you want it to work or not.

Wifi is regulated, by the way; the maximum power output is quite limited by the rules. This limits the effective range.

The mobile system gets to have much higher transmit power in its base stations, but they must be sited away from each other or use different bands. That allows the centrally coordinated TDMA to work.

There are many reasons why spectrum access is regulated. The most important one: The electromagnetic spectrum is shared, and at the moment we can only access a quite limited portion.

LTE operators spend a significant amount of money on providing (more or less) global coverage. Because they plan the infrastructure, they optimize spectrum access: you need overlapping cells, but avoid interference between cells.

This is what WiFi cannot do. In cities, you have way too many cells in one location. WiFi does not work well in these scenarios.

In fact, you can use WiFi as an access technology for LTE. The credentials are managed by LTE, but your phone will use the near WiFi Access Point. Some operators give such WiFi APs to their customers.

So, it is possible to combine WiFi and LTE characteristics already with today's technology. Some operators do that (search "pico cells", "WiFi offloading", "WiFi Aggregation").

WiFi also provides a local network, while LTE provides Internet access to anyone with a SIM. At least for some years, we'll still need this separation.

At last, we will always need somebody to build cell towers at highways and railways…