From what I've seen "unlimited" hosting providers will simply limit you in another dimension, which I think is just fine. For e.g I frequently see bandwidth sold in two tiers: you can have "unlimited" transfer at 100Mbit/s, or metered transfer at 1Gbit/s.
This approach let's the host plan capacity while giving users the illusion of unlimited bandwidth. Meanwhile customers that genuinely need the extra throughput can still get it at a premium.
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This is essentially what T-Mobile is doing, they're just not being transparent about it. You can have "unlimited" bandwidth at ~3.5Mbit/s (a 480p video stream), or you can pay a premium to saturate your link. They're just choosing to apply the throughput restriction to a specific class of traffic (HD streaming) because (A) it's a large fraction of their total traffic and (B) it's fairly easy to market to customers.
Of course there is no such thing as truly unlimited, but it can certainly be "unlimited" in one dimension. The issue here is that's not how T-Mobile is marketing it, they're marketing their network as "the fastest LTE network"[1] while also saying you have unlimited monthly bandwidth. The latter may be true, but it comes at the expense of throttling the throughput (for some fraction of subscribers); and once you throttle a subscriber you can no longer say you're providing them with access to "the fastest LTE network in America."
Yes, but there is such a thing as not placing a limit on the usage of a resource. I don't see it as deceptive if that's actually what they're doing. Sometimes "unlimited" is just a marketing term, other times it seems like a genuine statement of intent from the provider. Obviously I could be a dick and try to prove them wrong, but why?
Because you can't capacity plan when your provider says "unlimited" and then there is actually a limit, except because they don't tell you what it is, you don't know what it is until you hit it.
I understand that the word unlimited makes people feel good, but it shouldn't. Nothing is unlimited, ever. Just because they're not telling you what it is doesn't mean it isn't there.
Unmetered bandwidth that is capped at a gigabit or is physically incapable of going faster is not unlimited either. It's been throttled to only allow you to download a certain amount each month. It is also not unlimited, unless you consider a throttle to not be a limit.
Most cable modems, by the way, can go 3-5 times faster without the artificial throttles put on them by the providers. So even before Comcast started doing their stupid 1TB cap, they were already throttling your internet connection way below the possible speeds of the device.
That artificial throttle is not so artificial; they are charging you a lower amount because you are using less resources. The "last mile" is almost always bandwidth constrained, if you use less, then you pay less.
Most unlimited plans are outlined in the AUP/TOS. Further so long as you are not impacting other customers in the shared hosting, it is not generally an issue.
On the contrary, the TOS limitations are often an issue. They often regulate what you can use the data or hosting for. For instance, unlimited hosting plans often prohibit running download sites or being used as backup storage for yourself, to avoid you from using a lot of space or a lot of bandwidth. They also usually prohibit you from running cron jobs or game servers or chat bots which can be higher on other server resources.
"Unlimited" hosting plans are effectively geared for basic personal or small business websites only. And if you go over some soft limits they're almost certainly monitoring, they'll find an excuse in the TOS to disable your account.
I honestly find it, always and everywhere, to be deceptive marketing. There is no such thing as unlimited resources.