fwiw, i suspect the economics is even worse for the pubs. A pint takes the same amount of effort/labor to serve as 2/3, but you can't easily charge the same. So 90% of the volume in 2/3 pours is more labor for less money than if the beer were served in pints

An even bigger factor would be the cost of simply replacing the glassware in 90,000 on premise establishments.