Data caps are just documenting the reality that ISPs oversubscribe - if they sell a hundred 1Gb/s connections to a neighborhood, it's highly unlikely they're peering that neighborhood onto the Internet at large at 100Gb/s. I don't know what the current standard is, but in the past it's been 10/100 to 1 - so a hundred 1Gb/s connections might be sharing 1-10Gb/s of uplink; and if usage starts to saturate that they need a way of backing off that is "fair" - data caps are one of the ways they inform the customer of such.

I've seen it with my new fiber rollout - every single customer no matter their purchased speed had 1Gb up and down - as more customers came online and usage became higher, they're not limiting anyone, but you get closer to your advertised rate - but my upload is still faster than my download because most of my neighborhood is downloading, few are uploading.

I have 5 Gbps symmetric at home. I and my fiancee both work from home, so our backup fiber connection from another provider is 2 Gbps. We can also both tether to cell phones if necessary. We can get 5G home wireless Internet here, too, and we might ditch our 2 Gbps line in favor of that as a backup. We moved from Texas back home to Illinois last year, and one of the biggest considerations was who had service at what tiers due to remote work. Some of the houses we looked at in the same three-county area in the Chicago suburbs didn’t even have 5G home available (not from AT&T, Verizon, or T-Mobile anyway).

My parents have 5G wireless home as their primary connection, and that was only introduced in their area a couple of years ago. Before that, they could get dial-up, 512 kbps wireless with about a $1000 startup cost, ISDN (although the phone company really didn’t want to sell it to them), Starlink, or HughesNet. The folks across the asphalt road from them had 20 Mbps Ethernet over power lines years ago, and that’s now I think 250 Mbps. It’s a different power company, though, so they aren’t eligible.

Around 80% of the US population lives in large urban areas. The other 20% of the population range from smaller towns to living many kilometers from any town at all. There’s a lot of land in the US.

Our ISPs conspire to avoid competition (AKA "overbuilding") and so stuff like this just festers. It's truly a shame.