Some do some don't it depends on the local authority - some say there are compulsary some say they are optional. In the optional areas it is also upto the company you are working through/for if they want them or not. The area I worked (Wakefield) they were optional, but what I found was that customers didn't trust the meters and wanted to know what the fare was going to be before the journey commenced.

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What is life?
If not an excuse for death,
and what is death,
if not an escape from life?