Compliance with legal requirements in public spaces is rarely enough to guarantee access for everyone. People with invisible disabilities are often left out of designs. A focus on technical aspects often results in spaces that are still challenging for many. The American Society of Landscape Architects has a Universal Design page where they list some of the disabilities and impairments regularly overlooked. For example, dementia, deafness, vision loss, and autism. The classic 7 Principles of Universal Design are re-jigged to suit landscape design:
More detail on the above list is on their web page.You can also find more resources on their website including one specifically on Universal Design: Parks and Plazas with some nice case studies too.