The Tories, having made an utter, and completely deliberate, hash of the ESA and PIP disability benefits, are now proposing assessing both with a single assessment. Because merging everything else into Universal Credit's single assessment regime has worked so well. The idea is ridiculous, people apply for PIP when their disability makes them eligible, they apply for ESA when they are disabled and lose their job, the two things don't happen at the same time, but Tories....
To give some idea of the cross-over (or not), you get PIP for things like not being able to dress yourself or cook without help, or being able to walk less than 20m, whereas ESA can be taken away from you if the assessor imagines your problems with finding work would be solved by using a wheelchair which you don't have and which Wheelchair Services are refusing to give you. Yes, ESA assessments really do involve imaginary wheelchairs....
The best analogy I can think of is having a single test for both your driving and HGV licenses, and failing the driving test if the examiner doesn't thing you'd do well behind the wheel of a 50 tonne artic.
Anyway, my friend Lisa has started a petition to try and point out this is an utterly stupid idea proposed by people without a clue about disability, and a history of driving disabled people away from the benefits they're entitled to, so if you feel able to sign it (and are British or a UK resident), then please do.
DNS have an article here, suggesting the DWP incompetence backing this idea exceeds even usual levels.