I think it’s also because the best frequencies are already occupied by 2g/3g and 4g so it’s hard to provide good 5g coverage over large areas.

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.

2G is hard to shut down, because it just works, and many of the core services and old phones rely on it. It will survive 5G, 6G, 7G an other Gs.

2G is being shutdown (or already has) in many countries and those old phones and core services will need to be replaced.

We don't have it in the US, I remember being annoyed that there were no more cheap cellular modules for microcontrollers for a while.

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".)

4G is becoming the "baseline" and replacing 2G in many of those services, especially the "low energy" IoT implementations of LTE.

Australia (2018), New Zealand (2018), US (2017), Iceland (2025), Switzerland have shut down 2G networks.

In Norway, Telia shut down 2G in 2025, but Telenor is holding out until the end of 2027.

In Sweden, Telia is holding until 2027, and all other telcos have already switched it off.

France is shutting down 2G this year.

So the 2G shutdown is a real thing.

'best' is relative here; lower bands travel further, which is great for maximizing coverage footprint, but not great for high-density. Each node can only handle so much traffic, and you can pack them in more densely with short-range spectrum. mmWave really is the best frequency for very high density, high capacity networks, but the bottleneck is you have to deploy all the extra nodes to get the coverage.