Why may Workers be Occupational Immobile?

-In an Ideal World, Workers could have Transferrable Skills which means they are Good for a Number of Jobs -But Usually, that is not the Case. There are Specific Skills which may be going out of Fashion -Age also is a Factor. Younger Workers will be more Likely to Retrain than Older Workers -Some Jobs need High Level Qualifications and Personality Traits. This can make some Jobs Niche