Employment is a relationship between an employer and and employee. However governments see it differently, they see themselves involved in the work love triangle.
Government have their own goals in terms of how many are people are employed and how much they have to pay out and benefits. They feel they need to control/influence these numbers. Therefore when an employer and employee agree to a deal, they need to check with the Government to make sure that the government will allow the relationship.
The relationship with the employer and employee are voluntary, but the relationship with the government is not.
One of the ways that Government keeps control of the numbers employees or beneficiaries is to make it hard for employers to fire employees. (unfair dismissal/redundancy laws)
Another way that they could do this is to make it hard for employees to quit. (Unfair resignation/termination laws)
The employee would be obligated to compensate the employer for terminating their employment in the same way redundancy laws work.
Most of us would find the concept to be wrong, none of us would want to be trapped in employment we did not want to be in. It also smells of indentured labour.
But imposing the same conditions on an employer doesn't give us pause for thought, is that because fewer of us see ourselves as potential employers, or because we see them as the enemy?
This is an example of an unequal legal relationship. Usually instigated by people who call for more equality.
http://www.bbc.co.uk/news/business-31817007 lump of labour