Assuming the home test counts for your driving licence
Licence vision certificates must come from centres accredited by the licensing authority, which file results electronically — a standard home visit is not that. People pay AED 150–400 at home, then discover they still need the approved-centre test. Use the home visit as preparation, and ask about accreditation before booking if the licence is your whole reason.
Buying the comprehensive package when you needed a refraction
If you are young, healthy and simply need updated glasses, the full screening tier is usually money spent on reassurance rather than need. Match scope to situation: screening earns its price for over-60s, diabetics, and anyone with a glaucoma family history — not for every routine prescription top-up.
Accepting a verbal prescription or a 'we'll make your glasses' promise
Without a complete written prescription including pupillary distance, you are captive to the tester's own glasses pricing. The written document is what makes the market work for you — any optical shop can fill it. No paper, no payment.