As opposed to HF and UHF, which is a nasty collection of nested proprietary protocols that have been formally documented and given ISO numbers 
That has not been my experience. I have a metric shitton of readers of all shapes and sizes here - including a high-power HF reader - and the ones that consistencly work better at comparable power levels are LF. So much so that it’s the main reason why I decided to have myself cut wide open and implant a flexNExT, which frankly I could do without.
But you’re right, it might be the design of the readers. My little battery-powered locker cam-lock works surprisingly well with small HF glass implants, almost as good as any LF reader I’ve seen out there, and it’s obviously low-power. I guess it’s been designed right.
I’m hoping it defaults to working as a well-known passive transponder and goes into smart mode when it’s being read by a specialized reader. If it did, it’d be at least usable as a dumb chip. The marketing blurb doesn’t say, and I can’t find the technical spec sheet. I thought maybe you had already investigated this particular model, but apparently not.
Maybe I’ll ask Smartrac development samples, and what reading hardware they offer if I don’t want to roll my own. But there’s no point in contacting them if there’s no hope of implanting the thing.