Disability Insurance

I have been reading up on how disability insurance works in the US. There is a process for applying for Social Security Disability Insurance (SSDI), and often, applicants need help to take them through the process.
There are organisations that are set up to help potential applicants to complete paperwork and get the award that they are properly entitled to under the US social security system. Allsup.com are one such company who only charge a fee if the claim is successful. The awards eventually received are paid for through taxes, so the recipients must have paid into the 'FICA' tax system.