This is false, I live in Western Europe. Data cap is 50GB for a 30€ plan. This is farcry from "unlimited data plan" and there is 4G everywhere.
Sitting there streaming video content is a nonstarter just from a battery life point of view alone; I wouldn't do it even on Wi-Fi.
Speaking of which, 1.5Gb is enough that I don't bother looking for Wi-Fi hotspots.
The mobile plan is such that if it goes over the cap, it will just stop, rather than incurring extra charges. So until it stops, why would you mess with Wi-Fi.
Australia is a victim of its geography. (Plus last I heard the National fiber backbone didn’t go as planned either). I’m would expect a high bandwidth wired backbone is required to support scaling up mobile data throughput.