You're only thinking about the data fees. There's much more to an IoT offering that is priced into that cost. There's plenty of enterprise features, for example. Bulk management of SIMs is a huge one: setting data limits per-SIM or per-fleet, activating/deactivating them for seasonal devices or new distributions. Also consider SLAs for your very important data, or dedicated support from the carrier. You don't need any of these things when you are managing one phone, or even a family of phones, but they are essential for fleets of 100's or 1000's of devices.
Also, keep in mind that is data being sold to you for use only on their network. Roaming fees will be exorbitant if you need to go outside their network, which may be needed to reach rural areas, or when you have an asset tracker traveling between states or territories. Keep in mint that "normal priced data package" has very predictable usage — your phone is almost always online, meaning the backend infrastructure costs are low since it's not constantly going offline/online. The tower going out and verifying an IoT device should be on the network (especially if going through a roaming partner) is surprisingly expensive.
Also, keep in mind that is data being sold to you for use only on their network. Roaming fees will be exorbitant if you need to go outside their network, which may be needed to reach rural areas, or when you have an asset tracker traveling between states or territories. Keep in mint that "normal priced data package" has very predictable usage — your phone is almost always online, meaning the backend infrastructure costs are low since it's not constantly going offline/online. The tower going out and verifying an IoT device should be on the network (especially if going through a roaming partner) is surprisingly expensive.