According to Government statistics, over 20% of the UK's population live with a long term illness, impairment or disability, and EU data indicates that 5% of EU citizens do not use the internet at all because of a disability.
New requirements on website accessibility aim to address this problem by requiring more focus on making online material available to all. These affect the websites of public sector bodies, but also extend more widely to include some NGOs, as well as some educational and charitable organisations.
If you are building websites for organisations that may be receiving public funds, it makes sense to work out upfront whether the regulations might apply. If they do, compliance should be built into the project to avoid having to take remedial action later on.
Sebastian Allen-Johnstone discusses the regulations here.