Scanning a QR code is far faster than typing a URL, and you need some sort of a computer to access the URL anyway, so providing a human-readable URL doesn't achieve anything.
A relatively short url like restaurantname.menu is something a human can say and remember, so it does achieve something more useful than a QR code. I might even be able to type or speak a short url quicker into my phone than for me to find the QR code reader feature in my phone and point and hold my phone still.
