The building I live in has directional signs in the hallways at strategic locations to direct visitors to the correct unit. Apparently, some of the lettering on the signs began to fall off, likely due to incidental contact with passers-by.
In response, building management directed the engineering staff to protect the signs with acrylic covers. A simple, clean, and logical solution.
However, this solution now renders the signs completely inaccessible to visitors with impaired vision. The acrylic covers completely block the braille plates at the bottom of the signs.
The lesson here is fairly obvious. Accounting for accessibility takes effort. Whether you are working on documentation, software interfaces, or building signs, never forget your audience.