“Prescription glasses” only mean “glasses with optical properties”, so glasses that actually do anything with focus, as opposed to e.g. non-prescription sunglasses or non-prescription accessory glasses that people wear to look smart or something.
It doesn’t mean you need a prescription for them.
(That said: in some countries you need a prescription for your prescription glasses if you want your health insurance to pay for them.)
Because it’s not real. It’s purely for marketing, not for actual wide-spread implementation.
Even in the best of cases, even factoring in economy of scale and all that, a robot like that will cost upwards of €50k at least, probably closer to double that, will require constant maintainance, and the risk of vandalism or accidental damage is really high. And you’ll likely need a (skilled) human operator nearby anyway, because the delivery vehicle doesn’t drive itself.
The purpose of projects like this is marketing and public perception.
This robot is not meant to ever go mainstream. Maybe there will be a handful of routes where they will be implemented for marketing purposes, but like drone delivery and similar gimmicks, it won’t beat a criminally underpaid delivery human on price, and that’s the only metric that counts for a company like Amazon.