Fast LTE Modems/Hot Spots - Why So few an so Slow?

Disclaimer I am not in Oz right now and have signed up to an unlimited mobile internet plan on a network that supposedly support 600mbps.

I am currently using a Note 3 LTE cat4 as the hotspot for home internet. So I am now in search of some decent upgrade to a proper 4g modem and maybe router.

To my surprise, most of them are only cat4, cat6 and beyond are few and far between, restricted to a couple of more expensive netgears and huaweis.

So what gives? We already have plenty of cat12, cat16 phones around, so why not modems.