For mobile broadband, correct. For phones? There are plenty of "unlimited" deals.
"1 month Advanced plan
30GB Personal Hotspot"
What they all have, though is tethering limits (e.g. the 30Gb hotspot thing above). But on a phone, it's easy to get an "unlimited*" setup. That unlimited* isn't actually unlimited is a minor point in comparison to not being able to go over 50Gb on ANY 4G PROVIDER for mobile broadband no matter how much you're willing to pay.