Before ADA compliance became a factor in the creation of signs used everywhere, people would simply design signs that looked the way they liked it to look. There were no considerations for whether or not everyone could understand what was on the signs. The main thought when it came to sign designs in the past was whether or not these looked good and did these fit the image of the company that used them.
Color combinations in the past were based on aesthetics as well, and on what the company wanted these to be. There were no thoughts spared on whether the letters and numbers were legible enough with these resting on the selected color for the background. This usually led to some signs being difficult to read from a distance since the characters seemed to blend into the background of the sign.
Also worth mentioning is the use of substrates that are glossy and reflective. These materials often reflected light and made looking at the signs, as well as reading what was on them, pretty difficult. People would sometimes need to squint in order to understand what was written on these signs.
These are just some of the issues people faced when it came to signs that were made before the inception of the ADA. The signs that were being made were either difficult to read due to the color combinations, fonts used, the size of the characters, and many other issues. And these were difficult to read by everyone, not just those with visual impairments and disabilities.
These days, such problems are no longer an issue. With the ADA in place, signs are now governed by strict guidelines that make them easy to read and understand. Aside from the right color combinations that make the characters on these signs very legible even from a distance, these are also made using materials that are not reflective due to the rule regarding the use of non-gloss and matte finished substrates.
These signs are also made using fonts that are not fancy or weird looking, which make these easy to discern. This is appreciated by many, particularly by those who have blurred vision or other visual impairments that make recognizing letters and numbers from afar difficult when fancy fonts are used. Also making signs easier to read is the use of raised characters and the addition of braille translations. These are added onto signs for the benefit of those who have failing vision, and for those who have been declared legally blind.