Correct. That is probably why pagers are so popular with drug dealers.

The downside of a one way pager is that there is no way to know if the message got through. If you are in an elevator (or wherever) you simply never know of the page.

They still need to communicate two way to the cell tower to receive pages. Pages don't get flooded to every cell all over the world!

One way pagers only work in a particular area of the world. In that area all the transmitters send all the pages. Such systems do not scale all that well and as a result getting pager service over a wide area can be fairly expensive.

There's a few nationwide pager networks out there; they're quite easy to build without the task of making communication two way. Just set up a hundred or so watt UHF transmitter at an antenna farm, feed it with PSK or FSK from a satellite receiver, and boom! You just covered most of a large city.