Shopping trolleys for life is an interesting concept but as they havent found one inside a dolphin its probably not going to catch on just yet.
My mother used to steal the Free Ads newspaper for the local shop, she did it for years thinking it was free until the shopkeeper pointed out that she had to pay and that the word free meant that it was free to advertise in the paper.
To answer the question posed by the OP, you need to examine the word “stealing,” as I think this offers a solid clue to the answer.
The branded glasses are generally given to the pub for free from the brewery - so is it stealing if it has zero value? if it's not branded then it's highly likely the pub did have to pay for the glass, so would certainly call that stealing - and they can get expensive to replace
You know it's stealing because you got that stealy feeling when you sneeked it under your jacket and slipped out of the premises with one eye firmly on the staff
Using that logic, is it stealing if you take half the product from a shop with a buy one get one free offer? "No officer, these are all free ones not pay ones"
So, a pikey walks off with all your Christmas presents that you got from relatives... It’s not stealing, because you didn’t pay anything for them, yeah?
But the shop had to pay for those products and chooses to do an offer, so the product actually has a stock value to that shop. The pub hasn't paid for those glasses!
The beer companies aren't just going around random businesses and dumping worthless glasses off and then the pubs saying "wow what a coincidence we can actually put these to some use". They're part of a business relationship that has costs associated with it even if the glasses aren't individually itemised. But if you don't believe this, then don't just limit yourself to stealing glasses. You know those big umbrellas with beer logos on, same thing. Oh and another thing, almost everything you see a celebrity wearing or using was a gift/sponsorship, so feel free to take all that.