Blind windows

At the secondary school I attended in Kingston-upon-Thames, there was an old building that we simply referred to as "Elmfield". Here's what the British Listed Buildings website has to say about it:

1754. 3 storey house. Yellow brick, parapeted front with stone cornice and brick band at 1st floor level. South elevation has wide canted full height bay with 3 windows per floor. Two bays to the left of this and one to the right. West elevation of 5 bays with some blind windows. Sash windows with square gauged brick heads retaining glazing bars. Hipped slate roof.

Where the listing refers to 'blind windows' I think they must be talking about those windows that have been bricked up. Indeed, it was my curiosity around such windows in Elmfield that led me to learning about the window tax, which Wikipedia describes as:

... a property tax based on the number of windows in a house. It was a significant social, cultural, and architectural force in England, France, and Ireland during the 18th and 19th centuries. To avoid the tax, some houses from the period can be seen to have bricked-up window-spaces (ready to be glazed or reglazed at a later date). In England and Wales it was introduced in 1696 and was repealed 155 years later, in 1851.

I was reminded of this, today, by this beautiful old building in Salford, just off Trinity Way.

But look back at the Wikipedia entry: "...ready to be glazed or reglazed at a later date". Now that makes sense to me. So why do we see so many buildings that still have blind windows? Why weren't they reglazed? Can it be that the fact that they're listed prevents this? Surely not.