Changing the way things usually are done

According to the Job Accommodation Network, a reasonable accommodation "is a modification or adjustment to a job, the work environment, or the way things usually are done that enables a qualified individual with a disability to enjoy an equal employment opportunity. An equal employment opportunity means an opportunity to attain the same level of performance or to enjoy equal benefits and privileges of employment as are available to an average similarly-situated employee without a disability. The ADA requires reasonable accommodation in three aspects of employment:

• to ensure equal opportunity in the application process;
• to enable a qualified individual with a disability to perform the essential functions of a job; and
• to enable an employee with a disability to enjoy equal benefits and privileges of employment." http://askjan.org/LINKS/ADAtam1.html

Some nurses and nursing students are successful changing the "way things usually are done".....and some are not. I wonder why?