that is one big glass! 14 or 16 oz...
here we have the Imperial - it's about a 300 ml glass which is about a half-pint.
It's wrong to be misleading people, I agree...but I'm thinking it doesn't phase me at all because in Portugal people get away with crazy things.
Here is a funny ad from the most popular beer brand from Portugal...they do some good stuff.
(at the bottom it says "tastes like summer"...I'm sure you get the rest

)