Actually, aside from being aged 75+, there are a couple of other exemptions/discounts for the blind and people in residential care https://www.gov.uk/free-discount-tv-licence.
The thing that I don't understand now, is that you can watch iPlayer or live streaming without a licence. Not *legally*, but it just asks you if you have one and you say "yeah, sure, whatever". I wonder if any research has been done into the number of people watching like this without a licence? Wouldn't it help the revenues to have to login to the site with a valid TV licence code? (Obviously various controls to limit abuse, etc, etc).