Just let them, already.
Because the tech most certainly is NOT ready.
And when it proves an expensive failure, it'll be harder to justify the next (or any) such system in the future.
I have not yet once managed to get through Stansted airport facial-recognition, with or without-glasses, wearing the same T-shirt as in my passport photo, etc. etc. Not once. I ALWAYS stand there like an idiot for 5 minutes while it keeps trying, and then get pulled away by the woman STATIONED at the damn thing to take people to the "Whoops it didn't work line" where a human does the job (and which is always a long queue, not just individuals).
This stuff doesn't work any better than random chance, and certainly not better than a trained human. Stop it. Or rather - trial it all, see how useless it is, realise the salesmen lied, get over it and spend your next pot of money elsewhere to avoid a repeat embarrassment.