Well for one, it's terrible going through structure. It's bad at getting through thin wood framed construction, way worse with steel/glass and masonry which is common in JC. So even if they put the infrastructure in, and they'd have to put way more per square mile here than anywhere else, most people still can't use it unless they stand outside.

Secondly: Internet speeds are mostly a thing to make it easier for sales people to get gullible people to spend more money. Most CDN's limit anyone's connection to websites and services they host to 100Mbps by default, 500Mbps for a few premium services (and I can think of only a handful of things that actually do that). That's not just to control cost, it's the most rudimentary DDoS protection. Nobody needs more than that, so why bother even trying. 95% of what most people do in a day goes through one of the top 10 CDN's.

The highest bitrate 4k stream is about 50Mbps. For commercial services you can just freely subscribe to with a credit card it's 20Mbps (Disney+ I believe is the highest right now with 4k HDR). Even if a dozen people streamed in 4k @ 50Mbps, you're talking 600Mbps + 25% overhead for fun is still 725Mbps.. You're not even at a gigabit, and realistically no household is doing that.

Beyond that, services like Kaleidescape download passively overnight, but I'd bet nobody who's got Kaleidescape is using residential broadband, they've got business service with a proper SLA. So even on the high end: you don't need more than 500Mbps.

But sales people at every ISP now ask how many devices you own, and greater than 5-6 is going to recommend gigabit minimum.

That's where the money is. Convincing people who don't math good to spend more than they need. Do that over a few million customers, and you've got a perfectly legal high margin business.

There's no law requiring them to help you not overspend. These sales tactics are 100% legal and by the books.