To be filed under “things I didn’t know about that I prob­ably should’ve and that answer so many ques­tions: win­dow tax.

From wiki­pe­dia:

Prop­er­ties with between ten and twenty win­dows paid a total of four shil­lings, and those above twenty win­dows paid eight shil­lings.  The num­ber of win­dows that incurred tax was changed to seven in 1766 and eight in 1825. The flat-rate tax was changed to a vari­able rate, depend­ent on the prop­erty value, in 1778. People who were ineligible for church or poor rates, for reas­ons of poverty, were exempt from the win­dow tax.  Win­dow tax was rel­at­ively unin­trus­ive and easy to assess. The big­ger the house, the more win­dows it was likely to have, and the more tax the occu­pants would pay. Nev­er­the­less, the tax was unpop­u­lar, because it was seen by some as a tax on “light and air”.

The tax was imposed in Scot­land in the 1780s, instantly explain­ing (almost) all of the build­ings in Edin­burgh with bricked-up windows.

Addi­tion­ally, the tax is con­sidered to be a pos­sible ori­gin of the phrase “day­light rob­bery”, though this remains unproven.