3G has been shut down in several countries to free up frequencies. 2G was also shut down in several countries, it seems to be still up in most european countries with shut downs being scheduled in the next few years up to 2030.
At least in NZ around when they closed 2G the govt created a group of some kind which went around and put up a bunch of 4G towers in more remote areas, the key thing was the towers went owned on xyz company, so everyone who visits the area regardless of the telco they use get the same great signal.
*having said that, it's still sad 2G was closed, it had truly impressive coverage, with few cell towered required.
Is how it should be country wide in my opinion. Way too many towers up everywhere just so xyz company can get coverage there. Leaving no 1 company to have the "best" coverage.
2G also needs a tiny amount of spectrum in contrast to the newer standards, as it was designed almost exclusively for voice calls, where a few Kbps is sufficient for good quality speech. (And 64kbps, which is only 8KB/s, is considered "toll quality".)