I agree with you, but the way I see GP's point is that people are not running out of data because of non lazy loaded images. If they were, they'd be complaining about how little they can browse or buying bigger subscriptions.

It is also my experience that unlimited bundles (which aren't unlimited anyway, they're just limited to an amount that virtually nobody hits which is quite a difference from "we can make them use as much data as we want") are rare rather than the norm.