That does happen, but most employers are simply looking for qualified workers regardless of whether they have disabilities or not. Besides, the Americans with Disabilities Act (ADA) expressly forbids unjust discrimination and provides remedies to people who believe they have been discriminated against. Information on the ADA is available on the internet. The Equal Employment Opportunity Commission accepts complaints from workers and will investigate, and if warranted, ensure that steps are taken to remove the discrimination and ensure the employer adequately compensates the worker for anything due.
In addition, every state has an agency that provides Protection and Advocacy for individuals with disabilities who feel that they have been victims of discrimination. Contact the National Disability Rights Network for assistance.