I was actually told by my former employer that I couldn't be that sick if I was capable of calling in to say I was too ill to work. My contract stipulated that for sick leave to be granted it had to be the employee who called in, not a relative/friend/parent except in extreme circumstances. My role was largely telephone based and they said 'well if you can make one phonecall...'
Because making ONE five minute phonecall whilst laid in bed, arm aching so much from the effort of holding the phone to your ear it's almost making you cry means you're perfectly ok to sit in an office for 10 hours and make phone calls. Obviously.
When I first started there I found it bizarre how my colleagues kept going on about how I was such 'a bright girl'.
Then they made the 'but you're making a phonecall now... surely you're just imagining that you're more sick than you really are and you've let your Dr convince you of the same, they're not the experts people think they are you know' comment and I realised why! 
They even said 'oh, but your Dr's just a Dr... he doesn't know anything about working for this company or this industry' when my Dr and I refused to increase my working hours to the ones they wanted me to do.
And people wonder why those people with disabilities who may be able to do some work are struggling to find jobs.
This country needs to do a lot more to enable disabled people to work if they're capable of working - withdrawing their benefits isn't the answer. It's going to cause more stress and slow people's recovery down.
We're damned if we do and damned if we don't. If we don't work we're dirty rotten scroungers.
But people don't like wheelchairs and scooters, I've seen loads of 'they should get off the road' type comments from Daily mail readers et al. 'they're a menace' 'they take up loads of room on the bus'. So when we try to leave our homes to shop/go to work we're a menace. I read an article about a disabled man who crashed his adapted car 'I just don't think these people should be allowed to drive, they're not safe' (because car crashes are so rare amongst non disabled people!). An article about people with SN (specifically Dyspraxia) and the challenges they face learning to drive in the telegraph prompted 'they shouldn't be allowed on the road' comments.
So we're not allowed to use cars OR public transport to get to work if we're disabled...
Then there's articles about a problem 'caused' by a disabled person, like that stupid story about a hotel serving rotten food trying to blame the Chef with dyslexia as he 'couldn't read the labels'. Story was ridiculous, most kitchens have other systems in place (I have family who work as chefs) to make it easy to see how old food is. Also the Chef wasn't the only person in the kitchen and everyone could have seen/smelt the going off food anyway, regardless of sell by date. But it caused outraged comments 'disabled people shouldn't work... they're a risk' 'people with Dyslexia shouldn't do this kind of job... maybe they could sweep streets'
We just can't win.