A city street in Beatty is faster than a 8-lane highway in LA

I've always considered "#G" to be just a marketing term, and therefore largely meaningless.

It absolutely is.

I worked at a Telco that installed extremely old hardware, but because it was theoretically capable of achieving speeds that were similar to the low-end of 3G, they branded and marketed it as 3G.

Marketing loved it.

When you pulled out your phone it clearly said "2G" on the screen, but you were paying for 3G.

I'm assuming this is a case of unusually slow 4G, and not fast 3G? I travel frequently and I've noticed that sometimes my 4G speeds are very slow even when I have good signal strength, always in rural areas. I'm not sure what explains that.

The mast that your phone communicates with doesn't always have lots of fiber bandwidth. Sometimes it's only connected to other masts using microwave links (which could be outdated).