If there is no reason for caps, why wouldn’t one of these companies simply remove them, giving them a competitive advantage, and making them more money? Why would one company reject making more?

Maybe capless actually costs them more due to bad infrastructure, and they don’t see consumer demand for it? Forcing them to go capless would in that case result in higher prices.

Maybe they form a cartel and have collectively decided to keep caps. But why, if it doesn’t actually cost them more to remove the caps? And if it does, then prices would again rise if forced to go capless.

I’m confused where you believe consumers are given choice here.

I’m confused by you being confused. Consumers can pick a subscription with a data cap, or they can pick one without. Maybe you can clarify what you are confused about?

Clearly this is a marketing issue, not a technical one.

Why not both? Marketing can be a great way to work around technical issues, e.g. by steering consumer behaviour in a way that avoids the technical issues.

Also, just because one network has sufficient spare capacity to not steer users to reduce data usage does not mean that every network does that. In fact this is where choice comes in: I can pick a provider which spends more money on the network, resulting in a higher costs, but also higher caps. Or I can pick a provider that spends less on networks, resulting in lower costs, but needing caps to make sure the limited bandwidth is sufficient for all customers.

The industry has grown up since then, technically speaking, and there is no cause for data caps except to line the pockets of ISPs.

You mean except the reason I gave, and you ignored?

limiting how much I can use in total is bullshit. It’s not like it can run out.

There isn’t a limit because it “runs out” of data, but because of statistics, and the fact that bandwidth is limited.

Adding data caps reduces the total data volume, which in turn statistically reduces the average bandwidth used by all subscribers together (or whatever subset shares a connection).

Another approach would of course be to reduce the speed of each individual subscriber, but it may well be that subscribers prefer e.g. to be able to watch 10h of 4K video, vs 100h of 1080p video, despite the former being a lower volume of data.

Essentially it comes down to whether you want lots of data, but slowly, or less data but quickly (assuming the same price).

It seems weird to ban consumer choice here.

A related, but different, question is if the consumer truly has a choice in the US. But to me it would make more sense to solve the competition question instead of even further restrict consumer choices for those that do have a choice.