Les stocks et les flux ?  You can be unemployed any number of times but are unlikely to be really disabled more than once (unless you're Djibril Cissé that is...).  Also, I'm willing to bet (though not look for figures, heaven forbid!) that a lot of the disabled went through a long bout of unemployment especially when the disability is due to a psychological condition.
My point is that the average Joe is being rational in fearing unemployment, which he will likely face at some point, which people around him are facing, as being more likely than being crippled physically or mentally.

As I comment above, we need to be clear about "disabled". A person in a wheelchair may be very capable of working, wish to work, find work. Same for other types of disability. These people suffer from some degree of permanent disability but are not necessarily classified as unfit for work.

What may operate as camouflage for long-term unemployment in the statistics is a medical decision the person is unfit for work. (For psychological reasons, for example, or chronic backache, etc). This may not be a lifelong decision, and will probably be subject to regular re-appraisal. But it takes an unemployed person off the unemployment statistics and on to another set that is not given public prominence...