The employers will do their best to keep wages low and workers in a state of oppression. Having workers "on contract" or employing them as casual or temporary workers are all ways the the employers use to create job insecurity.
Employers will do what they can to reduce labour cost (and therefore increase their profits) and increasing the exploitation of labour is just part of this process.
Are you a worker or self-employed?
In order to answer this question it is necessary to determine whether you work under a contract of service (employees) or under a contract for services (self-employed, independent contractor). For tax and National Insurance purposes, there is no statutory definition of a contract of service or of a contract for services. What the parties call their relationship, or what they consider it to be, is not conclusive. It is the reality of the relationship that matters.
In order to determine the nature of a contract, it is necessary to apply common law principles. The courts have, over the years, laid down some factors and tests that are relevant, which are included in the overview below.
As a general guide as to whether a worker is an employee or self-employed …
... if the answer is 'Yes' to all of the following questions, then the worker is probably an employee:
... if the answer is 'Yes' to all of the following questions, it will usually mean that the worker is self-employed:
Can they hire someone to do the work or engage helpers at their own expense?
There may be situations where a worker can say "yes" to some of the examples given in both of these lists. In cases like that the court has to take a balance of what its the most dominant feature.
If you are not sure, go and ask the union.
In 1991, the Communications Workers Union won an interesting case in the Industrial Court against Diana Investments Limited (IRO 3/1991). It addressed in detail this question of what is casual and temporary work and in its decision, the Court provided the following useful definiton:
"According to the principles of good industrial relations practice, a casual worker is a person who is employed on an irregular or intermittent basis and a temporary worker is a person who is employed for a specific duration or for the completion of a specific assignment."